diff --git a/accessible/atk/AccessibleWrap.cpp b/accessible/atk/AccessibleWrap.cpp
index 5f98faac2cc5..cca059e9b34c 100644
--- a/accessible/atk/AccessibleWrap.cpp
+++ b/accessible/atk/AccessibleWrap.cpp
@@ -12,6 +12,7 @@
 #include "nsAccUtils.h"
 #include "nsIAccessibleRelation.h"
 #include "nsIAccessibleTable.h"
+#include "ProxyAccessible.h"
 #include "RootAccessible.h"
 #include "nsIAccessibleValue.h"
 #include "nsMai.h"
@@ -20,6 +21,7 @@
 #include "nsAutoPtr.h"
 #include "prprf.h"
 #include "nsStateMap.h"
+#include "mozilla/a11y/Platform.h"
 #include "Relation.h"
 #include "RootAccessible.h"
 #include "States.h"
@@ -133,9 +135,13 @@ struct MaiAtkObject
    * The AccessibleWrap whose properties and features are exported
    * via this object instance.
    */
-  AccessibleWrap* accWrap;
+  uintptr_t accWrap;
 };
 
+// This is or'd with the pointer in MaiAtkObject::accWrap if the wrap-ee is a
+// proxy.
+static const uintptr_t IS_PROXY = 1;
+
 struct MaiAtkObjectClass
 {
     AtkObjectClass parent_class;
@@ -248,7 +254,7 @@ AccessibleWrap::ShutdownAtkObject()
 {
     if (mAtkObject) {
         if (IS_MAI_OBJECT(mAtkObject)) {
-            MAI_ATK_OBJECT(mAtkObject)->accWrap = nullptr;
+            MAI_ATK_OBJECT(mAtkObject)->accWrap = 0;
         }
         SetMaiHyperlink(nullptr);
         g_object_unref(mAtkObject);
@@ -582,8 +588,7 @@ initializeCB(AtkObject *aAtkObj, gpointer aData)
         ATK_OBJECT_CLASS(parent_class)->initialize(aAtkObj, aData);
 
   /* initialize object */
-  MAI_ATK_OBJECT(aAtkObj)->accWrap =
-    static_cast<AccessibleWrap*>(aData);
+  MAI_ATK_OBJECT(aAtkObj)->accWrap = reinterpret_cast<uintptr_t>(aData);
 }
 
 void
@@ -591,7 +596,7 @@ finalizeCB(GObject *aObj)
 {
     if (!IS_MAI_OBJECT(aObj))
         return;
-    NS_ASSERTION(MAI_ATK_OBJECT(aObj)->accWrap == nullptr, "AccWrap NOT null");
+    NS_ASSERTION(MAI_ATK_OBJECT(aObj)->accWrap == 0, "AccWrap NOT null");
 
     // call parent finalize function
     // finalize of GObjectClass will unref the accessible parent if has
@@ -663,25 +668,33 @@ getDescriptionCB(AtkObject *aAtkObj)
 AtkRole
 getRoleCB(AtkObject *aAtkObj)
 {
-  AccessibleWrap* accWrap = GetAccessibleWrap(aAtkObj);
-  if (!accWrap)
-    return ATK_ROLE_INVALID;
-
-#ifdef DEBUG
-  NS_ASSERTION(nsAccUtils::IsTextInterfaceSupportCorrect(accWrap),
-      "Does not support nsIAccessibleText when it should");
-#endif
-
   if (aAtkObj->role != ATK_ROLE_INVALID)
     return aAtkObj->role;
 
+  AccessibleWrap* accWrap = GetAccessibleWrap(aAtkObj);
+  a11y::role role;
+  if (!accWrap) {
+    ProxyAccessible* proxy = GetProxy(aAtkObj);
+    if (!proxy)
+      return ATK_ROLE_INVALID;
+
+    role = proxy->Role();
+  } else {
+#ifdef DEBUG
+    NS_ASSERTION(nsAccUtils::IsTextInterfaceSupportCorrect(accWrap),
+                 "Does not support nsIAccessibleText when it should");
+#endif
+
+    role = accWrap->Role();
+  }
+
 #define ROLE(geckoRole, stringRole, atkRole, macRole, \
              msaaRole, ia2Role, nameRule) \
   case roles::geckoRole: \
     aAtkObj->role = atkRole; \
     break;
 
-  switch (accWrap->Role()) {
+  switch (role) {
 #include "RoleMap.h"
     default:
       MOZ_CRASH("Unknown role.");
@@ -946,7 +959,13 @@ AccessibleWrap*
 GetAccessibleWrap(AtkObject* aAtkObj)
 {
   NS_ENSURE_TRUE(IS_MAI_OBJECT(aAtkObj), nullptr);
-  AccessibleWrap* accWrap = MAI_ATK_OBJECT(aAtkObj)->accWrap;
+
+  // Make sure its native is an AccessibleWrap not a proxy.
+  if (MAI_ATK_OBJECT(aAtkObj)->accWrap & IS_PROXY)
+    return nullptr;
+
+    AccessibleWrap* accWrap =
+      reinterpret_cast<AccessibleWrap*>(MAI_ATK_OBJECT(aAtkObj)->accWrap);
 
   // Check if the accessible was deconstructed.
   if (!accWrap)
@@ -961,6 +980,49 @@ GetAccessibleWrap(AtkObject* aAtkObj)
   return accWrap;
 }
 
+ProxyAccessible*
+GetProxy(AtkObject* aObj)
+{
+  if (!aObj || !(MAI_ATK_OBJECT(aObj)->accWrap & IS_PROXY))
+    return nullptr;
+
+  return reinterpret_cast<ProxyAccessible*>(MAI_ATK_OBJECT(aObj)->accWrap
+      & ~IS_PROXY);
+}
+
+static uint16_t
+GetInterfacesForProxy(ProxyAccessible* aProxy)
+{
+  return MAI_INTERFACE_COMPONENT;
+}
+
+void
+a11y::ProxyCreated(ProxyAccessible* aProxy)
+{
+  GType type = GetMaiAtkType(GetInterfacesForProxy(aProxy));
+  NS_ASSERTION(type, "why don't we have a type!");
+
+  AtkObject* obj =
+    reinterpret_cast<AtkObject *>
+    (g_object_new(type, nullptr));
+  if (!obj)
+    return;
+
+  atk_object_initialize(obj, aProxy);
+  obj->role = ATK_ROLE_INVALID;
+  obj->layer = ATK_LAYER_INVALID;
+  aProxy->SetWrapper(reinterpret_cast<uintptr_t>(obj) | IS_PROXY);
+}
+
+void
+a11y::ProxyDestroyed(ProxyAccessible* aProxy)
+{
+  auto obj = reinterpret_cast<MaiAtkObject*>(aProxy->GetWrapper() & ~IS_PROXY);
+  obj->accWrap = 0;
+  g_object_unref(obj);
+  aProxy->SetWrapper(0);
+}
+
 nsresult
 AccessibleWrap::HandleAccEvent(AccEvent* aEvent)
 {
diff --git a/accessible/atk/AccessibleWrap.h b/accessible/atk/AccessibleWrap.h
index 5518a80bd5d8..95d03c5fc16c 100644
--- a/accessible/atk/AccessibleWrap.h
+++ b/accessible/atk/AccessibleWrap.h
@@ -97,7 +97,7 @@ private:
 
   static EAvailableAtkSignals gAvailableAtkSignals;
 
-  uint16_t CreateMaiInterfaces(void);
+  uint16_t CreateMaiInterfaces();
 };
 
 } // namespace a11y
diff --git a/accessible/atk/moz.build b/accessible/atk/moz.build
index 37ec9e8fded5..96fc8cee15d7 100644
--- a/accessible/atk/moz.build
+++ b/accessible/atk/moz.build
@@ -35,6 +35,7 @@ LOCAL_INCLUDES += [
     '/accessible/base',
     '/accessible/generic',
     '/accessible/html',
+    '/accessible/ipc',
     '/accessible/xpcom',
     '/accessible/xul',
     '/other-licenses/atk-1.0',
diff --git a/accessible/atk/nsMai.h b/accessible/atk/nsMai.h
index 5de552ac67a5..6338a3492bae 100644
--- a/accessible/atk/nsMai.h
+++ b/accessible/atk/nsMai.h
@@ -13,6 +13,12 @@
 
 #include "AccessibleWrap.h"
 
+namespace mozilla {
+namespace a11y {
+class ProxyAccessible;
+}
+}
+
 #define MAI_TYPE_ATK_OBJECT             (mai_atk_object_get_type ())
 #define MAI_ATK_OBJECT(obj)             (G_TYPE_CHECK_INSTANCE_CAST ((obj), \
                                          MAI_TYPE_ATK_OBJECT, MaiAtkObject))
@@ -29,6 +35,7 @@
 GType mai_atk_object_get_type(void);
 GType mai_util_get_type();
 mozilla::a11y::AccessibleWrap* GetAccessibleWrap(AtkObject* aAtkObj);
+mozilla::a11y::ProxyAccessible* GetProxy(AtkObject* aAtkObj);
 
 extern int atkMajorVersion, atkMinorVersion;
 
diff --git a/accessible/base/AccEvent.h b/accessible/base/AccEvent.h
index f97b1fc4e01b..ee28efa511b6 100644
--- a/accessible/base/AccEvent.h
+++ b/accessible/base/AccEvent.h
@@ -232,6 +232,8 @@ public:
   bool IsShow() const { return mEventType == nsIAccessibleEvent::EVENT_SHOW; }
   bool IsHide() const { return mEventType == nsIAccessibleEvent::EVENT_HIDE; }
 
+  Accessible* Parent() const { return mParent; }
+
 protected:
   nsCOMPtr<nsINode> mNode;
   nsRefPtr<Accessible> mParent;
diff --git a/accessible/base/DocManager.cpp b/accessible/base/DocManager.cpp
index eed51d5ca01a..5ff0f3350459 100644
--- a/accessible/base/DocManager.cpp
+++ b/accessible/base/DocManager.cpp
@@ -8,6 +8,7 @@
 #include "ApplicationAccessible.h"
 #include "ARIAMap.h"
 #include "DocAccessible-inl.h"
+#include "DocAccessibleChild.h"
 #include "nsAccessibilityService.h"
 #include "RootAccessibleWrap.h"
 
@@ -27,6 +28,8 @@
 #include "nsServiceManagerUtils.h"
 #include "nsIWebProgress.h"
 #include "nsCoreUtils.h"
+#include "nsXULAppAPI.h"
+#include "mozilla/dom/ContentChild.h"
 
 using namespace mozilla;
 using namespace mozilla::a11y;
@@ -418,6 +421,12 @@ DocManager::CreateDocOrRootAccessible(nsIDocument* aDocument)
     docAcc->FireDelayedEvent(nsIAccessibleEvent::EVENT_REORDER,
                              ApplicationAcc());
 
+    if (IPCAccessibilityActive()) {
+      DocAccessibleChild* ipcDoc = new DocAccessibleChild(docAcc);
+      docAcc->SetIPCDoc(ipcDoc);
+    auto contentChild = dom::ContentChild::GetSingleton();
+    contentChild->SendPDocAccessibleConstructor(ipcDoc, nullptr, 0);
+    }
   } else {
     parentDocAcc->BindChildDocument(docAcc);
   }
diff --git a/accessible/base/DocManager.h b/accessible/base/DocManager.h
index 13e80a602372..69193820eb67 100644
--- a/accessible/base/DocManager.h
+++ b/accessible/base/DocManager.h
@@ -17,6 +17,7 @@ namespace a11y {
 
 class Accessible;
 class DocAccessible;
+class DocAccessibleParent;
 
 /**
  * Manage the document accessible life cycle.
@@ -65,6 +66,25 @@ public:
     RemoveListeners(aDocument);
   }
 
+  /*
+   * Notification that a top level document in a content process has gone away.
+   */
+  void RemoteDocShutdown(DocAccessibleParent* aDoc)
+  {
+    DebugOnly<bool> result = mRemoteDocuments.RemoveElement(aDoc);
+    MOZ_ASSERT(result, "Why didn't we find the document!");
+  }
+
+  /*
+   * Notify of a new top level document in a content process.
+   */
+  void RemoteDocAdded(DocAccessibleParent* aDoc)
+  {
+    MOZ_ASSERT(!mRemoteDocuments.Contains(aDoc),
+               "How did we already have the doc!");
+    mRemoteDocuments.AppendElement(aDoc);
+  }
+
 #ifdef DEBUG
   bool IsProcessingRefreshDriverNotification() const;
 #endif
@@ -144,6 +164,11 @@ private:
 #endif
 
   DocAccessibleHashtable mDocAccessibleCache;
+
+  /*
+   * The list of remote top level documents.
+   */
+  nsTArray<DocAccessibleParent*> mRemoteDocuments;
 };
 
 /**
diff --git a/accessible/base/EventQueue.cpp b/accessible/base/EventQueue.cpp
index 6338785e49c9..31c4687ffdfb 100644
--- a/accessible/base/EventQueue.cpp
+++ b/accessible/base/EventQueue.cpp
@@ -8,6 +8,7 @@
 #include "Accessible-inl.h"
 #include "nsEventShell.h"
 #include "DocAccessible.h"
+#include "DocAccessibleChild.h"
 #include "nsAccessibilityService.h"
 #include "nsTextEquivUtils.h"
 #ifdef A11Y_LOG
@@ -555,5 +556,15 @@ EventQueue::ProcessEventQueue()
 
     if (!mDocument)
       return;
+
+    if (IPCAccessibilityActive()) {
+    DocAccessibleChild* ipcDoc = mDocument->IPCDoc();
+      if (event->mEventType == nsIAccessibleEvent::EVENT_SHOW)
+        ipcDoc->ShowEvent(downcast_accEvent(event));
+      else if (event->mEventType == nsIAccessibleEvent::EVENT_HIDE)
+        ipcDoc->SendHideEvent(reinterpret_cast<uintptr_t>(event->GetAccessible()));
+      else
+        ipcDoc->SendEvent(event->GetEventType());
+    }
   }
 }
diff --git a/accessible/base/NotificationController.cpp b/accessible/base/NotificationController.cpp
index 82a591ab72c1..8dee12548eae 100644
--- a/accessible/base/NotificationController.cpp
+++ b/accessible/base/NotificationController.cpp
@@ -6,9 +6,11 @@
 #include "NotificationController.h"
 
 #include "DocAccessible-inl.h"
+#include "DocAccessibleChild.h"
 #include "TextLeafAccessible.h"
 #include "TextUpdater.h"
 
+#include "mozilla/dom/ContentChild.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/Telemetry.h"
 
@@ -217,8 +219,19 @@ NotificationController::WillRefresh(mozilla::TimeStamp aTime)
     if (ownerContent) {
       Accessible* outerDocAcc = mDocument->GetAccessible(ownerContent);
       if (outerDocAcc && outerDocAcc->AppendChild(childDoc)) {
-        if (mDocument->AppendChildDocument(childDoc))
+        if (mDocument->AppendChildDocument(childDoc)) {
+          if (IPCAccessibilityActive()) {
+            DocAccessibleChild* ipcDoc = new DocAccessibleChild(childDoc);
+            childDoc->SetIPCDoc(ipcDoc);
+            auto contentChild = dom::ContentChild::GetSingleton();
+            DocAccessibleChild* parentIPCDoc = mDocument->IPCDoc();
+            uint64_t id = reinterpret_cast<uintptr_t>(outerDocAcc->UniqueID());
+            contentChild->SendPDocAccessibleConstructor(ipcDoc, parentIPCDoc,
+                                                        id);
+          }
+
           continue;
+        }
 
         outerDocAcc->RemoveChild(childDoc);
       }
diff --git a/accessible/base/Platform.h b/accessible/base/Platform.h
index fa56963fdbed..41954be440d8 100644
--- a/accessible/base/Platform.h
+++ b/accessible/base/Platform.h
@@ -7,6 +7,8 @@
 namespace mozilla {
 namespace a11y {
 
+class ProxyAccessible;
+
 enum EPlatformDisabledState {
   ePlatformIsForceEnabled = -1,
   ePlatformIsEnabled = 0,
@@ -47,6 +49,17 @@ void PlatformInit();
  */
 void PlatformShutdown();
 
+/**
+ * called when a new ProxyAccessible is created, so the platform may setup a
+ * wrapper for it, or take other action.
+ */
+void ProxyCreated(ProxyAccessible*);
+
+/**
+ * Called just before a ProxyAccessible is destroyed so its wrapper can be
+ * disposed of and other action taken.
+ */
+void ProxyDestroyed(ProxyAccessible*);
 } // namespace a11y
 } // namespace mozilla
 
diff --git a/accessible/base/Role.h b/accessible/base/Role.h
index 2cd378d64482..0d5746f3dc13 100644
--- a/accessible/base/Role.h
+++ b/accessible/base/Role.h
@@ -783,7 +783,9 @@ enum Role {
   /**
    * Represent a keyboard or keypad key (ARIA role "key").
    */
-  KEY = 129
+  KEY = 129,
+
+  LAST_ROLE = KEY
 };
 
 } // namespace role
diff --git a/accessible/base/moz.build b/accessible/base/moz.build
index e31cf3e5c4c3..0dad363cc445 100644
--- a/accessible/base/moz.build
+++ b/accessible/base/moz.build
@@ -60,6 +60,7 @@ if CONFIG['A11Y_LOG']:
 LOCAL_INCLUDES += [
     '/accessible/generic',
     '/accessible/html',
+    '/accessible/ipc',
     '/accessible/xpcom',
     '/accessible/xul',
     '/dom/xbl',
@@ -93,3 +94,5 @@ FINAL_LIBRARY = 'xul'
 
 if CONFIG['MOZ_ENABLE_GTK']:
     CXXFLAGS += CONFIG['MOZ_CAIRO_CFLAGS']
+
+include('/ipc/chromium/chromium-config.mozbuild')
diff --git a/accessible/base/nsAccessibilityService.h b/accessible/base/nsAccessibilityService.h
index d466e6f457b0..fc616748d50c 100644
--- a/accessible/base/nsAccessibilityService.h
+++ b/accessible/base/nsAccessibilityService.h
@@ -238,6 +238,19 @@ GetAccService()
   return nsAccessibilityService::gAccessibilityService;
 }
 
+/**
+ * Return true if we're in a content process and not B2G.
+ */
+inline bool
+IPCAccessibilityActive()
+{
+#ifdef MOZ_B2G
+  return false;
+#else
+  return XRE_GetProcessType() != GeckoProcessType_Default;
+#endif
+}
+
 /**
  * Map nsIAccessibleEvents constants to strings. Used by
  * nsIAccessibleRetrieval::getStringEventType() method.
diff --git a/accessible/generic/DocAccessible.cpp b/accessible/generic/DocAccessible.cpp
index bd63bf17ec95..c950f45b76f5 100644
--- a/accessible/generic/DocAccessible.cpp
+++ b/accessible/generic/DocAccessible.cpp
@@ -6,6 +6,7 @@
 #include "Accessible-inl.h"
 #include "AccIterator.h"
 #include "DocAccessible-inl.h"
+#include "DocAccessibleChild.h"
 #include "HTMLImageMapAccessible.h"
 #include "nsAccCache.h"
 #include "nsAccessiblePivot.h"
@@ -83,7 +84,7 @@ DocAccessible::
   mScrollPositionChangedTicks(0),
   mLoadState(eTreeConstructionPending), mDocFlags(0), mLoadEventType(0),
   mVirtualCursor(nullptr),
-  mPresShell(aPresShell)
+  mPresShell(aPresShell), mIPCDoc(nullptr)
 {
   mGenericTypes |= eDocument;
   mStateFlags |= eNotNodeMapEntry;
@@ -473,6 +474,12 @@ DocAccessible::Shutdown()
 
   mChildDocuments.Clear();
 
+  // XXX thinking about ordering?
+  if (IPCAccessibilityActive()) {
+    DocAccessibleChild::Send__delete__(mIPCDoc);
+    MOZ_ASSERT(!mIPCDoc);
+  }
+
   if (mVirtualCursor) {
     mVirtualCursor->RemoveObserver(this);
     mVirtualCursor = nullptr;
@@ -1446,6 +1453,13 @@ DocAccessible::DoInitialUpdate()
     nsRefPtr<AccReorderEvent> reorderEvent = new AccReorderEvent(Parent());
     ParentDocument()->FireDelayedEvent(reorderEvent);
   }
+
+  uint32_t childCount = ChildCount();
+  for (uint32_t i = 0; i < childCount; i++) {
+    Accessible* child = GetChildAt(i);
+    nsRefPtr<AccShowEvent> event = new AccShowEvent(child, child->GetContent());
+  FireDelayedEvent(event);
+  }
 }
 
 void
diff --git a/accessible/generic/DocAccessible.h b/accessible/generic/DocAccessible.h
index 4d7858c1cfa0..42b655e69a55 100644
--- a/accessible/generic/DocAccessible.h
+++ b/accessible/generic/DocAccessible.h
@@ -33,6 +33,7 @@ namespace a11y {
 
 class DocManager;
 class NotificationController;
+class DocAccessibleChild;
 class RelatedAccIterator;
 template<class Class, class Arg>
 class TNotification;
@@ -519,6 +520,20 @@ protected:
    */
   bool IsLoadEventTarget() const;
 
+  /**
+   * If this document is in a content process return the object responsible for
+   * communicating with the main process for it.
+   */
+  DocAccessibleChild* IPCDoc() const { return mIPCDoc; }
+
+  /*
+   * Set the object responsible for communicating with the main process on
+   * behalf of this document.
+   */
+  void SetIPCDoc(DocAccessibleChild* aIPCDoc) { mIPCDoc = aIPCDoc; }
+
+  friend class DocAccessibleChild;
+
   /**
    * Used to fire scrolling end event after page scroll.
    *
@@ -642,6 +657,9 @@ protected:
 private:
 
   nsIPresShell* mPresShell;
+
+  // Exclusively owned by IPDL so don't manually delete it!
+  DocAccessibleChild* mIPCDoc;
 };
 
 inline DocAccessible*
diff --git a/accessible/generic/moz.build b/accessible/generic/moz.build
index 236715bda01d..3b393c650fb6 100644
--- a/accessible/generic/moz.build
+++ b/accessible/generic/moz.build
@@ -28,6 +28,7 @@ UNIFIED_SOURCES += [
 LOCAL_INCLUDES += [
     '/accessible/base',
     '/accessible/html',
+    '/accessible/ipc',
     '/accessible/xpcom',
     '/accessible/xul',
     '/content/base/src',
@@ -54,3 +55,5 @@ else:
     ]
 
 FINAL_LIBRARY = 'xul'
+
+include('/ipc/chromium/chromium-config.mozbuild')
diff --git a/accessible/ipc/DocAccessibleChild.cpp b/accessible/ipc/DocAccessibleChild.cpp
new file mode 100644
index 000000000000..5070b1fe9739
--- /dev/null
+++ b/accessible/ipc/DocAccessibleChild.cpp
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "DocAccessibleChild.h"
+
+#include "Accessible-inl.h"
+
+namespace mozilla {
+namespace a11y {
+
+void
+SerializeTree(Accessible* aRoot, nsTArray<AccessibleData>& aTree)
+{
+  uint64_t id = reinterpret_cast<uint64_t>(aRoot->UniqueID());
+  uint32_t role = aRoot->Role();
+  uint32_t childCount = aRoot->ChildCount();
+
+  nsString name;
+  aRoot->Name(name);
+  aTree.AppendElement(AccessibleData(id, role, childCount, name));
+  for (uint32_t i = 0; i < childCount; i++)
+    SerializeTree(aRoot->GetChildAt(i), aTree);
+}
+
+void
+DocAccessibleChild::ShowEvent(AccShowEvent* aShowEvent)
+{
+  Accessible* parent = aShowEvent->Parent();
+  uint64_t parentID = parent->IsDoc() ? 0 : reinterpret_cast<uint64_t>(parent->UniqueID());
+  uint32_t idxInParent = aShowEvent->GetAccessible()->IndexInParent();
+  nsTArray<AccessibleData> shownTree;
+  ShowEventData data(parentID, idxInParent, shownTree);
+  SerializeTree(aShowEvent->GetAccessible(), data.NewTree());
+  SendShowEvent(data);
+}
+}
+}
diff --git a/accessible/ipc/DocAccessibleChild.h b/accessible/ipc/DocAccessibleChild.h
new file mode 100644
index 000000000000..50fdcc7cfd1f
--- /dev/null
+++ b/accessible/ipc/DocAccessibleChild.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_a11y_DocAccessibleChild_h
+#define mozilla_a11y_DocAccessibleChild_h
+
+#include "mozilla/a11y/DocAccessible.h"
+#include "mozilla/a11y/PDocAccessibleChild.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+namespace a11y {
+class AccShowEvent;
+
+  /*
+   * These objects handle content side communication for an accessible document,
+   * and their lifetime is the same as the document they represent.
+   */
+class DocAccessibleChild : public PDocAccessibleChild
+{
+public:
+  DocAccessibleChild(DocAccessible* aDoc) :
+    mDoc(aDoc)
+  { MOZ_COUNT_CTOR(DocAccessibleChild); }
+  ~DocAccessibleChild()
+  {
+    mDoc->SetIPCDoc(nullptr);
+    MOZ_COUNT_DTOR(DocAccessibleChild);
+  }
+
+  void ShowEvent(AccShowEvent* aShowEvent);
+
+private:
+  DocAccessible* mDoc;
+};
+
+}
+}
+
+#endif
diff --git a/accessible/ipc/DocAccessibleParent.cpp b/accessible/ipc/DocAccessibleParent.cpp
new file mode 100644
index 000000000000..3bbec6e54117
--- /dev/null
+++ b/accessible/ipc/DocAccessibleParent.cpp
@@ -0,0 +1,114 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "DocAccessibleParent.h"
+#include "nsAutoPtr.h"
+#include "mozilla/a11y/Platform.h"
+
+namespace mozilla {
+namespace a11y {
+
+bool
+DocAccessibleParent::RecvShowEvent(const ShowEventData& aData)
+{
+  if (aData.NewTree().IsEmpty()) {
+    NS_ERROR("no children being added");
+    return false;
+  }
+
+  ProxyAccessible* parent = nullptr;
+  if (aData.ID()) {
+    ProxyEntry* e = mAccessibles.GetEntry(aData.ID());
+    if (e)
+      parent = e->mProxy;
+  } else {
+    parent = this;
+  }
+
+  // XXX This should really never happen, but sometimes we fail to fire the
+  // required show events.
+  if (!parent) {
+    NS_ERROR("adding child to unknown accessible");
+    return false;
+  }
+
+  uint32_t newChildIdx = aData.Idx();
+  if (newChildIdx > parent->ChildrenCount()) {
+    NS_ERROR("invalid index to add child at");
+    return false;
+  }
+
+  uint32_t consumed = AddSubtree(parent, aData.NewTree(), 0, newChildIdx);
+  MOZ_ASSERT(consumed == aData.NewTree().Length());
+  for (uint32_t i = 0; i < consumed; i++) {
+    uint64_t id = aData.NewTree()[i].ID();
+    MOZ_ASSERT(mAccessibles.GetEntry(id));
+  }
+
+  return consumed;
+}
+
+uint32_t
+DocAccessibleParent::AddSubtree(ProxyAccessible* aParent,
+                                const nsTArray<a11y::AccessibleData>& aNewTree,
+                                uint32_t aIdx, uint32_t aIdxInParent)
+{
+  if (aNewTree.Length() <= aIdx) {
+    NS_ERROR("bad index in serialized tree!");
+    return 0;
+  }
+
+  const AccessibleData& newChild = aNewTree[aIdx];
+  if (newChild.Role() > roles::LAST_ROLE) {
+    NS_ERROR("invalid role");
+    return 0;
+  }
+
+  auto role = static_cast<a11y::role>(newChild.Role());
+  ProxyAccessible* newProxy =
+    new ProxyAccessible(newChild.ID(), aParent, this, role, newChild.Name());
+  aParent->AddChildAt(aIdxInParent, newProxy);
+  mAccessibles.PutEntry(newChild.ID())->mProxy = newProxy;
+  ProxyCreated(newProxy);
+
+  uint32_t accessibles = 1;
+  uint32_t kids = newChild.ChildrenCount();
+  for (uint32_t i = 0; i < kids; i++) {
+    uint32_t consumed = AddSubtree(newProxy, aNewTree, aIdx + accessibles, i);
+    if (!consumed)
+      return 0;
+
+    accessibles += consumed;
+  }
+
+  MOZ_ASSERT(newProxy->ChildrenCount() == kids);
+
+  return accessibles;
+}
+
+bool
+DocAccessibleParent::RecvHideEvent(const uint64_t& aRootID)
+{
+  ProxyEntry* rootEntry = mAccessibles.GetEntry(aRootID);
+  if (!rootEntry) {
+    NS_ERROR("invalid root being removed!");
+    return true;
+  }
+
+  ProxyAccessible* root = rootEntry->mProxy;
+  if (!root) {
+    NS_ERROR("invalid root being removed!");
+    return true;
+  }
+
+  ProxyAccessible* parent = root->Parent();
+  parent->RemoveChild(root);
+  root->Shutdown();
+
+  return true;
+}
+}
+}
diff --git a/accessible/ipc/DocAccessibleParent.h b/accessible/ipc/DocAccessibleParent.h
new file mode 100644
index 000000000000..b92a5e0ac127
--- /dev/null
+++ b/accessible/ipc/DocAccessibleParent.h
@@ -0,0 +1,141 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_a11y_DocAccessibleParent_h
+#define mozilla_a11y_DocAccessibleParent_h
+
+#include "nsAccessibilityService.h"
+#include "ProxyAccessible.h"
+#include "mozilla/a11y/PDocAccessibleParent.h"
+#include "nsClassHashtable.h"
+#include "nsHashKeys.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+namespace a11y {
+
+/*
+ * These objects live in the main process and comunicate with and represent
+ * an accessible document in a content process.
+ */
+class DocAccessibleParent : public ProxyAccessible,
+    public PDocAccessibleParent
+{
+public:
+  DocAccessibleParent() :
+    mParentDoc(nullptr)
+  { MOZ_COUNT_CTOR_INHERITED(DocAccessibleParent, ProxyAccessible); }
+  ~DocAccessibleParent()
+  {
+    MOZ_COUNT_DTOR_INHERITED(DocAccessibleParent, ProxyAccessible);
+    MOZ_ASSERT(mChildDocs.Length() == 0);
+    MOZ_ASSERT(!mParentDoc);
+  }
+
+  /*
+   * Called when a message from a document in a child process notifies the main
+   * process it is firing an event.
+   */
+  virtual bool RecvEvent(const uint32_t& aType) MOZ_OVERRIDE
+  {
+    return true;
+  }
+
+  virtual bool RecvShowEvent(const ShowEventData& aData) MOZ_OVERRIDE;
+  virtual bool RecvHideEvent(const uint64_t& aRootID) MOZ_OVERRIDE;
+
+  virtual void ActorDestroy(ActorDestroyReason aWhy) MOZ_OVERRIDE
+  {
+    MOZ_ASSERT(mChildDocs.IsEmpty(),
+               "why wheren't the child docs destroyed already?");
+    mParentDoc ? mParentDoc->RemoveChildDoc(this)
+      : GetAccService()->RemoteDocShutdown(this);
+  }
+
+  /*
+   * Return the main processes representation of the parent document (if any)
+   * of the document this object represents.
+   */
+  DocAccessibleParent* Parent() const { return mParentDoc; }
+
+  /*
+   * Called when a document in a content process notifies the main process of a
+   * new child document.
+   */
+  bool AddChildDoc(DocAccessibleParent* aChildDoc, uint64_t aParentID)
+  {
+    ProxyAccessible* outerDoc = mAccessibles.GetEntry(aParentID)->mProxy;
+    if (!outerDoc)
+      return false;
+
+    aChildDoc->mParent = outerDoc;
+    outerDoc->SetChildDoc(aChildDoc);
+    mChildDocs.AppendElement(aChildDoc);
+    aChildDoc->mParentDoc = this;
+    return true;
+  }
+
+  /*
+   * Called when the document in the content process this object represents
+   * notifies the main process a child document has been removed.
+   */
+  void RemoveChildDoc(DocAccessibleParent* aChildDoc)
+  {
+    aChildDoc->mParent->SetChildDoc(nullptr);
+    mChildDocs.RemoveElement(aChildDoc);
+    aChildDoc->mParentDoc = nullptr;
+    MOZ_ASSERT(aChildDoc->mChildDocs.Length() == 0);
+  }
+
+  void RemoveAccessible(ProxyAccessible* aAccessible)
+  {
+    MOZ_ASSERT(mAccessibles.GetEntry(aAccessible->ID()));
+    mAccessibles.RemoveEntry(aAccessible->ID());
+  }
+
+private:
+
+  class ProxyEntry : public PLDHashEntryHdr
+  {
+  public:
+    ProxyEntry(const void*) : mProxy(nullptr) {}
+    ProxyEntry(ProxyEntry&& aOther) :
+      mProxy(aOther.mProxy) { aOther.mProxy = nullptr; }
+    ~ProxyEntry() { delete mProxy; }
+
+    typedef uint64_t KeyType;
+    typedef const void* KeyTypePointer;
+
+    bool KeyEquals(const void* aKey) const
+    { return mProxy->ID() == (uint64_t)aKey; }
+
+    static const void* KeyToPointer(uint64_t aKey) { return (void*)aKey; }
+
+    static PLDHashNumber HashKey(const void* aKey) { return (uint64_t)aKey; }
+
+    enum { ALLOW_MEMMOVE = true };
+
+    ProxyAccessible* mProxy;
+  };
+
+  uint32_t AddSubtree(ProxyAccessible* aParent,
+                      const nsTArray<AccessibleData>& aNewTree, uint32_t aIdx,
+                      uint32_t aIdxInParent);
+
+  nsTArray<DocAccessibleParent*> mChildDocs;
+  DocAccessibleParent* mParentDoc;
+
+  /*
+   * Conceptually this is a map from IDs to proxies, but we store the ID in the
+   * proxy object so we can't use a real map.
+   */
+  nsTHashtable<ProxyEntry> mAccessibles;
+};
+
+}
+}
+
+#endif
diff --git a/accessible/ipc/PDocAccessible.ipdl b/accessible/ipc/PDocAccessible.ipdl
new file mode 100644
index 000000000000..b3328b31b680
--- /dev/null
+++ b/accessible/ipc/PDocAccessible.ipdl
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PContent;
+
+namespace mozilla {
+namespace a11y {
+
+struct AccessibleData
+{
+  uint64_t ID;
+  uint32_t Role;
+  uint32_t ChildrenCount;
+  nsString Name;
+};
+
+struct ShowEventData
+{
+  uint64_t ID;
+  uint32_t Idx;
+  AccessibleData[] NewTree;
+};
+
+protocol PDocAccessible
+{
+  manager PContent;
+
+parent:
+  __delete__();
+
+  /*
+   * Notify the parent process the document in the child process is firing an
+   * event.
+   */
+  Event(uint32_t type);
+  ShowEvent(ShowEventData data);
+  HideEvent(uint64_t aRootID);
+};
+
+}
+}
diff --git a/accessible/ipc/ProxyAccessible.cpp b/accessible/ipc/ProxyAccessible.cpp
new file mode 100644
index 000000000000..5af1aa41d8fb
--- /dev/null
+++ b/accessible/ipc/ProxyAccessible.cpp
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ProxyAccessible.h"
+#include "DocAccessibleParent.h"
+#include "mozilla/a11y/Platform.h"
+
+namespace mozilla {
+namespace a11y {
+
+void
+ProxyAccessible::Shutdown()
+{
+  MOZ_ASSERT(!mOuterDoc);
+
+  uint32_t childCount = mChildren.Length();
+  for (uint32_t idx = 0; idx < childCount; idx++)
+    mChildren[idx]->Shutdown();
+
+  mChildren.Clear();
+  ProxyDestroyed(this);
+  mDoc->RemoveAccessible(this);
+}
+
+void
+ProxyAccessible::SetChildDoc(DocAccessibleParent* aParent)
+{
+  if (aParent) {
+    MOZ_ASSERT(mChildren.IsEmpty());
+    mChildren.AppendElement(aParent);
+    mOuterDoc = true;
+  } else {
+    MOZ_ASSERT(mChildren.Length() == 1);
+    mChildren.Clear();
+    mOuterDoc = false;
+  }
+}
+}
+}
diff --git a/accessible/ipc/ProxyAccessible.h b/accessible/ipc/ProxyAccessible.h
new file mode 100644
index 000000000000..126e9bfc1cc5
--- /dev/null
+++ b/accessible/ipc/ProxyAccessible.h
@@ -0,0 +1,88 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_a11y_ProxyAccessible_h
+#define mozilla_a11y_ProxyAccessible_h
+
+#include "mozilla/a11y/Role.h"
+#include "nsString.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace a11y {
+
+class DocAccessibleParent;
+
+class ProxyAccessible
+{
+public:
+
+  ProxyAccessible(uint64_t aID, ProxyAccessible* aParent,
+                  DocAccessibleParent* aDoc, role aRole,
+                  const nsString& aName) :
+     mParent(aParent), mDoc(aDoc), mID(aID), mRole(aRole), mOuterDoc(false), mName(aName)
+  {
+    MOZ_COUNT_CTOR(ProxyAccessible);
+  }
+  ~ProxyAccessible() { MOZ_COUNT_DTOR(ProxyAccessible); }
+
+  void AddChildAt(uint32_t aIdx, ProxyAccessible* aChild)
+  { mChildren.InsertElementAt(aIdx, aChild); }
+
+  uint32_t ChildrenCount() const { return mChildren.Length(); }
+
+  void Shutdown();
+
+  void SetChildDoc(DocAccessibleParent*);
+
+  /**
+   * Remove The given child.
+   */
+  void RemoveChild(ProxyAccessible* aChild)
+    { mChildren.RemoveElement(aChild); }
+
+  /**
+   * Return the proxy for the parent of the wrapped accessible.
+   */
+  ProxyAccessible* Parent() const { return mParent; }
+
+  /**
+   * Get the role of the accessible we're proxying.
+   */
+  role Role() const { return mRole; }
+
+  /**
+   * Allow the platform to store a pointers worth of data on us.
+   */
+  uintptr_t GetWrapper() const { return mWrapper; }
+  void SetWrapper(uintptr_t aWrapper) { mWrapper = aWrapper; }
+
+  /*
+   * Return the ID of the accessible being proxied.
+   */
+  uint64_t ID() const { return mID; }
+
+protected:
+  ProxyAccessible() :
+    mParent(nullptr), mDoc(nullptr) { MOZ_COUNT_CTOR(ProxyAccessible); }
+
+protected:
+  ProxyAccessible* mParent;
+
+private:
+  nsTArray<ProxyAccessible*> mChildren;
+  DocAccessibleParent* mDoc;
+  uintptr_t mWrapper;
+  uint64_t mID;
+  role mRole : 31;
+  bool mOuterDoc : 1;
+  nsString mName;
+};
+
+}
+}
+
+#endif
diff --git a/accessible/ipc/moz.build b/accessible/ipc/moz.build
new file mode 100644
index 000000000000..340e79bf2984
--- /dev/null
+++ b/accessible/ipc/moz.build
@@ -0,0 +1,31 @@
+# -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+IPDL_SOURCES += ['PDocAccessible.ipdl']
+
+# with --disable-accessibility we need to compile PDocAccessible.ipdl, but not
+# the C++.
+if CONFIG['ACCESSIBILITY']:
+    EXPORTS.mozilla.a11y += [
+        'DocAccessibleChild.h',
+        'DocAccessibleParent.h',
+        'ProxyAccessible.h'
+    ]
+
+    SOURCES += [
+        'DocAccessibleChild.cpp',
+        'DocAccessibleParent.cpp',
+        'ProxyAccessible.cpp'
+    ]
+
+    LOCAL_INCLUDES += [
+        '../base',
+        '../generic',
+    ]
+
+    FINAL_LIBRARY = 'xul'
+
+include('/ipc/chromium/chromium-config.mozbuild')
diff --git a/accessible/mac/Platform.mm b/accessible/mac/Platform.mm
index 98bbac02a9b9..4d82f2c5e836 100644
--- a/accessible/mac/Platform.mm
+++ b/accessible/mac/Platform.mm
@@ -33,6 +33,15 @@ PlatformShutdown()
 {
 }
 
+void
+ProxyCreated(ProxyAccessible*)
+{
+}
+
+void
+ProxyDestroyed(ProxyAccessible*)
+{
+}
 }
 }
 
diff --git a/accessible/moz.build b/accessible/moz.build
index 44f345780018..993d2202937f 100644
--- a/accessible/moz.build
+++ b/accessible/moz.build
@@ -15,7 +15,7 @@ elif toolkit == 'cocoa':
 else:
     DIRS += ['other']
 
-DIRS += ['base', 'generic', 'html', 'interfaces', 'jsat', 'xpcom']
+DIRS += ['base', 'generic', 'html', 'interfaces', 'ipc', 'jsat', 'xpcom']
 
 if CONFIG['MOZ_XUL']:
     DIRS += ['xul']
diff --git a/accessible/other/Platform.cpp b/accessible/other/Platform.cpp
index 87c9fc6071f8..768f687c738c 100644
--- a/accessible/other/Platform.cpp
+++ b/accessible/other/Platform.cpp
@@ -18,3 +18,13 @@ void
 a11y::PlatformShutdown()
 {
 }
+
+void
+a11y::ProxyCreated(ProxyAccessible*)
+{
+}
+
+void
+a11y::ProxyDestroyed(ProxyAccessible*)
+{
+}
diff --git a/accessible/windows/msaa/Platform.cpp b/accessible/windows/msaa/Platform.cpp
index 263eb1a4d130..0ed1f5ffc073 100644
--- a/accessible/windows/msaa/Platform.cpp
+++ b/accessible/windows/msaa/Platform.cpp
@@ -34,3 +34,12 @@ a11y::PlatformShutdown()
   nsWinUtils::ShutdownWindowEmulation();
 }
 
+void
+a11y::ProxyCreated(ProxyAccessible*)
+{
+}
+
+void
+a11y::ProxyDestroyed(ProxyAccessible*)
+{
+}
diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index bfd13920ad45..d5132dcb5aec 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -19,6 +19,9 @@
 #include "TabChild.h"
 
 #include "mozilla/Attributes.h"
+#ifdef ACCESSIBILITY
+#include "mozilla/a11y/DocAccessibleChild.h"
+#endif
 #include "mozilla/Preferences.h"
 #include "mozilla/dom/ContentBridgeChild.h"
 #include "mozilla/dom/ContentBridgeParent.h"
@@ -731,6 +734,22 @@ ContentChild::InitXPCOM()
     InitOnContentProcessCreated();
 }
 
+a11y::PDocAccessibleChild*
+ContentChild::AllocPDocAccessibleChild(PDocAccessibleChild*, const uint64_t&)
+{
+  MOZ_ASSERT(false, "should never call this!");
+  return nullptr;
+}
+
+bool
+ContentChild::DeallocPDocAccessibleChild(a11y::PDocAccessibleChild* aChild)
+{
+#ifdef ACCESSIBILITY
+  delete static_cast<mozilla::a11y::DocAccessibleChild*>(aChild);
+#endif
+  return true;
+}
+
 PMemoryReportRequestChild*
 ContentChild::AllocPMemoryReportRequestChild(const uint32_t& aGeneration,
                                              const bool &aAnonymize,
diff --git a/dom/ipc/ContentChild.h b/dom/ipc/ContentChild.h
index dcf3dc638fed..a8bdf7a1303b 100644
--- a/dom/ipc/ContentChild.h
+++ b/dom/ipc/ContentChild.h
@@ -382,6 +382,8 @@ public:
                                          const uint64_t& aID,
                                          const bool& aIsForApp,
                                          const bool& aIsForBrowser) MOZ_OVERRIDE;
+    virtual PDocAccessibleChild* AllocPDocAccessibleChild(PDocAccessibleChild*, const uint64_t&) MOZ_OVERRIDE;
+    virtual bool DeallocPDocAccessibleChild(PDocAccessibleChild*) MOZ_OVERRIDE;
 
     void GetAvailableDictionaries(InfallibleTArray<nsString>& aDictionaries);
 
diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index d9bdcf1713c3..4f87332b34bf 100755
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -30,6 +30,10 @@
 #include "CrashReporterParent.h"
 #include "IHistory.h"
 #include "mozIApplication.h"
+#ifdef ACCESSIBILITY
+#include "mozilla/a11y/DocAccessibleParent.h"
+#include "nsAccessibilityService.h"
+#endif
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/dom/DataStoreService.h"
 #include "mozilla/dom/DOMStorageIPC.h"
@@ -2706,6 +2710,42 @@ ContentParent::Observe(nsISupports* aSubject,
     return NS_OK;
 }
 
+  a11y::PDocAccessibleParent*
+ContentParent::AllocPDocAccessibleParent(PDocAccessibleParent* aParent, const uint64_t&)
+{
+#ifdef ACCESSIBILITY
+  return new a11y::DocAccessibleParent();
+#else
+  return nullptr;
+#endif
+}
+
+bool
+ContentParent::DeallocPDocAccessibleParent(PDocAccessibleParent* aParent)
+{
+#ifdef ACCESSIBILITY
+  delete static_cast<a11y::DocAccessibleParent*>(aParent);
+#endif
+  return true;
+}
+
+bool
+ContentParent::RecvPDocAccessibleConstructor(PDocAccessibleParent* aDoc, PDocAccessibleParent* aParentDoc, const uint64_t& aParentID)
+{
+#ifdef ACCESSIBILITY
+  auto doc = static_cast<a11y::DocAccessibleParent*>(aDoc);
+  if (aParentDoc) {
+    MOZ_ASSERT(aParentID);
+    auto parentDoc = static_cast<a11y::DocAccessibleParent*>(aParentDoc);
+    return parentDoc->AddChildDoc(doc, aParentID);
+  } else {
+    MOZ_ASSERT(!aParentID);
+    GetAccService()->RemoteDocAdded(doc);
+  }
+#endif
+  return true;
+}
+
 PCompositorParent*
 ContentParent::AllocPCompositorParent(mozilla::ipc::Transport* aTransport,
                                       base::ProcessId aOtherProcess)
diff --git a/dom/ipc/ContentParent.h b/dom/ipc/ContentParent.h
index c38705e98149..b6bfefdc2de5 100644
--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -679,6 +679,11 @@ private:
                           int32_t* aSliceRefCnt,
                           bool* aResult) MOZ_OVERRIDE;
 
+    virtual PDocAccessibleParent* AllocPDocAccessibleParent(PDocAccessibleParent*, const uint64_t&) MOZ_OVERRIDE;
+    virtual bool DeallocPDocAccessibleParent(PDocAccessibleParent*) MOZ_OVERRIDE;
+    virtual bool RecvPDocAccessibleConstructor(PDocAccessibleParent* aDoc,
+                                               PDocAccessibleParent* aParentDoc, const uint64_t& aParentID) MOZ_OVERRIDE;
+
     // If you add strong pointers to cycle collected objects here, be sure to
     // release these objects in ShutDownProcess.  See the comment there for more
     // details.
diff --git a/dom/ipc/PContent.ipdl b/dom/ipc/PContent.ipdl
index c8d3defa0767..cfb59d0a134b 100644
--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -14,6 +14,7 @@ include protocol PCompositor;
 include protocol PContentBridge;
 include protocol PCycleCollectWithLogs;
 include protocol PCrashReporter;
+include protocol PDocAccessible;
 include protocol PExternalHelperApp;
 include protocol PDeviceStorageRequest;
 include protocol PFileDescriptorSet;
@@ -333,6 +334,7 @@ prio(normal upto high) intr protocol PContent
     manages PCellBroadcast;
     manages PCrashReporter;
     manages PCycleCollectWithLogs;
+    manages PDocAccessible;
     manages PDeviceStorageRequest;
     manages PFileSystemRequest;
     manages PExternalHelperApp;
@@ -491,6 +493,14 @@ child:
     OnAppThemeChanged();
 
 parent:
+    /**
+     * Tell the parent process a new accessible document has been created.
+     * aParentDoc is the accessible document it was created in if any, and
+     * aParentAcc is the id of the accessible in that document the new document
+     * is a child of.
+     */
+    PDocAccessible(nullable PDocAccessible aParentDoc, uint64_t aParentAcc);
+
     /**
      * Tell the content process some attributes of itself.  This is
      * among the first information queried by content processes after
diff --git a/toolkit/toolkit.mozbuild b/toolkit/toolkit.mozbuild
index 79a078b42da7..2dcea0d5122c 100644
--- a/toolkit/toolkit.mozbuild
+++ b/toolkit/toolkit.mozbuild
@@ -118,6 +118,8 @@ if CONFIG['MOZ_UNIVERSALCHARDET']:
 
 if CONFIG['ACCESSIBILITY']:
     DIRS += ['/accessible']
+else:
+    DIRS += ['/accessible/ipc']
 
 # toolkit