Bug 1191491 - Do not dispatch an audio-playback notification when swapping browsers; r=smaug

We send a pagehide event during swapping docshell frame loaders, and
before this patch we would not be able to differentiate this event with
the one that we send when navigating away from a page, so we would
incorrectly dispatch an audio-playback notification indicating that
audio playback has stopped.  This patch adds a flag to the root docshell
when the frame loader swapping is in progress and disables the above
behavior when that flag is set.

browser/base/content/test/general/browser_audioTabIcon.js

@@ -115,12 +115,28 @@ function* test_swapped_browser(oldTab, newBrowser, isPlaying) {
     return (event.detail.changed.indexOf("soundplaying") >= 0 || !isPlaying) &&
            event.detail.changed.indexOf("muted") >= 0;
   });
+  let AudioPlaybackPromise = new Promise(resolve => {
+    let observer = (subject, topic, data) => {
+      ok(false, "Should not see an audio-playback notification");
+    };
+    Services.obs.addObserver(observer, "audio-playback", false);
+    setTimeout(() => {
+      Services.obs.removeObserver(observer, "audio-playback");
+      resolve();
+    }, 100);
+  });
 
   gBrowser.swapBrowsersAndCloseOther(newTab, oldTab);
   yield AttrChangePromise;
 
   ok(newTab.hasAttribute("muted"), "Expected the correct muted attribute on the new tab");
   is(newTab.hasAttribute("soundplaying"), isPlaying, "Expected the correct soundplaying attribute on the new tab");
+
+  // Wait to see if an audio-playback event is dispatched.  This should not happen!
+  yield AudioPlaybackPromise;
+
+  ok(newTab.hasAttribute("muted"), "Expected the correct muted attribute on the new tab");
+  is(newTab.hasAttribute("soundplaying"), isPlaying, "Expected the correct soundplaying attribute on the new tab");
 }
 
 function* test_browser_swapping(tab, browser) {

docshell/base/nsDocShell.cpp

@@ -900,6 +900,7 @@ nsDocShell::nsDocShell()
   , mUseRemoteTabs(false)
   , mDeviceSizeIsPageSize(false)
   , mWindowDraggingAllowed(false)
+  , mInFrameSwap(false)
   , mCanExecuteScripts(false)
   , mFiredUnloadEvent(false)
   , mEODForCurrentDocument(false)
@@ -14074,3 +14075,16 @@ nsDocShell::GetPaymentRequestId(nsAString& aPaymentRequestId)
   aPaymentRequestId = GetInheritedPaymentRequestId();
   return NS_OK;
 }
+
+bool
+nsDocShell::InFrameSwap()
+{
+  nsRefPtr<nsDocShell> shell = this;
+  do {
+    if (shell->mInFrameSwap) {
+      return true;
+    }
+    shell = shell->GetParentDocshell();
+  } while (shell);
+  return false;
+}

docshell/base/nsDocShell.h

@@ -258,6 +258,12 @@ public:
   // is no longer applied
   void NotifyAsyncPanZoomStopped();
 
+  void SetInFrameSwap(bool aInSwap)
+  {
+    mInFrameSwap = aInSwap;
+  }
+  bool InFrameSwap();
+
 private:
   // An observed docshell wrapper is created when recording markers is enabled.
   mozilla::UniquePtr<mozilla::ObservedDocShell> mObserved;
@@ -900,6 +906,7 @@ protected:
   bool mUseRemoteTabs;
   bool mDeviceSizeIsPageSize;
   bool mWindowDraggingAllowed;
+  bool mInFrameSwap;
 
   // Because scriptability depends on the mAllowJavascript values of our
   // ancestors, we cache the effective scriptability and recompute it when

dom/base/nsFrameLoader.cpp

@@ -987,8 +987,8 @@ nsFrameLoader::SwapWithOtherLoader(nsFrameLoader* aOther,
     return NS_ERROR_DOM_SECURITY_ERR;
   }
 
-  nsCOMPtr<nsIDocShell> ourDocshell = GetExistingDocShell();
-  nsCOMPtr<nsIDocShell> otherDocshell = aOther->GetExistingDocShell();
+  nsRefPtr<nsDocShell> ourDocshell = static_cast<nsDocShell*>(GetExistingDocShell());
+  nsRefPtr<nsDocShell> otherDocshell = static_cast<nsDocShell*>(aOther->GetExistingDocShell());
   if (!ourDocshell || !otherDocshell) {
     // How odd
     return NS_ERROR_NOT_IMPLEMENTED;
@@ -1120,6 +1120,8 @@ nsFrameLoader::SwapWithOtherLoader(nsFrameLoader* aOther,
     return NS_ERROR_NOT_IMPLEMENTED;
   }
   mInSwap = aOther->mInSwap = true;
+  ourDocshell->SetInFrameSwap(true);
+  otherDocshell->SetInFrameSwap(true);
 
   // Fire pageshow events on still-loading pages, and then fire pagehide
   // events.  Note that we do NOT fire these in the normal way, but just fire
@@ -1132,26 +1134,32 @@ nsFrameLoader::SwapWithOtherLoader(nsFrameLoader* aOther,
   nsIFrame* ourFrame = ourContent->GetPrimaryFrame();
   nsIFrame* otherFrame = otherContent->GetPrimaryFrame();
   if (!ourFrame || !otherFrame) {
-    mInSwap = aOther->mInSwap = false;
     nsContentUtils::FirePageShowEvent(ourDocshell, ourEventTarget, true);
     nsContentUtils::FirePageShowEvent(otherDocshell, otherEventTarget, true);
+    mInSwap = aOther->mInSwap = false;
+    ourDocshell->SetInFrameSwap(false);
+    otherDocshell->SetInFrameSwap(false);
     return NS_ERROR_NOT_IMPLEMENTED;
   }
 
   nsSubDocumentFrame* ourFrameFrame = do_QueryFrame(ourFrame);
   if (!ourFrameFrame) {
-    mInSwap = aOther->mInSwap = false;
     nsContentUtils::FirePageShowEvent(ourDocshell, ourEventTarget, true);
     nsContentUtils::FirePageShowEvent(otherDocshell, otherEventTarget, true);
+    mInSwap = aOther->mInSwap = false;
+    ourDocshell->SetInFrameSwap(false);
+    otherDocshell->SetInFrameSwap(false);
     return NS_ERROR_NOT_IMPLEMENTED;
   }
 
   // OK.  First begin to swap the docshells in the two nsIFrames
   rv = ourFrameFrame->BeginSwapDocShells(otherFrame);
   if (NS_FAILED(rv)) {
-    mInSwap = aOther->mInSwap = false;
     nsContentUtils::FirePageShowEvent(ourDocshell, ourEventTarget, true);
     nsContentUtils::FirePageShowEvent(otherDocshell, otherEventTarget, true);
+    mInSwap = aOther->mInSwap = false;
+    ourDocshell->SetInFrameSwap(false);
+    otherDocshell->SetInFrameSwap(false);
     return rv;
   }
 
@@ -1258,6 +1266,8 @@ nsFrameLoader::SwapWithOtherLoader(nsFrameLoader* aOther,
   nsContentUtils::FirePageShowEvent(otherDocshell, otherEventTarget, true);
 
   mInSwap = aOther->mInSwap = false;
+  ourDocshell->SetInFrameSwap(false);
+  otherDocshell->SetInFrameSwap(false);
   return NS_OK;
 }
 

dom/html/HTMLMediaElement.cpp

@@ -103,6 +103,7 @@ static PRLogModuleInfo* gMediaElementEventsLog;
 
 #include "nsIPermissionManager.h"
 #include "nsContentTypeParser.h"
+#include "nsDocShell.h"
 
 #include "mozilla/EventStateManager.h"
 
@@ -4013,7 +4014,14 @@ void HTMLMediaElement::NotifyOwnerDocumentActivityChanged()
   if (pauseElement && mAudioChannelAgent) {
     // If the element is being paused since we are navigating away from the
     // document, notify the audio channel agent.
-    NotifyAudioChannelAgent(false);
+    // Be careful to ignore this event during a docshell frame swap.
+    auto docShell = static_cast<nsDocShell*>(OwnerDoc()->GetDocShell());
+    if (!docShell) {
+      return;
+    }
+    if (!docShell->InFrameSwap()) {
+      NotifyAudioChannelAgent(false);
+    }
   }
 }
 

dom/ipc/TabChild.cpp

@@ -2392,11 +2392,18 @@ TabChild::RecvSwappedWithOtherRemoteLoader()
     return true;
   }
 
+  nsRefPtr<nsDocShell> docShell = static_cast<nsDocShell*>(ourDocShell.get());
+
   nsCOMPtr<EventTarget> ourEventTarget = ourWindow->GetParentTarget();
 
+  docShell->SetInFrameSwap(true);
+
   nsContentUtils::FirePageShowEvent(ourDocShell, ourEventTarget, false);
   nsContentUtils::FirePageHideEvent(ourDocShell, ourEventTarget);
   nsContentUtils::FirePageShowEvent(ourDocShell, ourEventTarget, true);
+
+  docShell->SetInFrameSwap(false);
+
   return true;
 }