From 99112e99315d26794c1d29a4d7ba9780d37d2e59 Mon Sep 17 00:00:00 2001
From: Ryan VanderMeulen <ryanvm@gmail.com>
Date: Tue, 17 Oct 2017 10:07:55 -0400
Subject: [PATCH] Backed out 5 changesets (bug 1407351) for causing bug 1409395
 and breaking nightlies.

Backed out changeset e6ee25ad6a9f (bug 1407351)
Backed out changeset 8e04412824b5 (bug 1407351)
Backed out changeset effeee94316e (bug 1407351)
Backed out changeset a53f34a45f9b (bug 1407351)
Backed out changeset 86a360e12b8a (bug 1407351)
---
 browser/base/content/browser-menubar.inc      |  6 ++
 browser/base/content/browser-sets.inc         |  4 +
 browser/base/content/browser.js               | 37 +++++++++
 browser/base/content/browser.xul              |  6 ++
 browser/base/content/tabbrowser.xml           | 25 ++++++-
 .../customizableui/CustomizableUI.jsm         | 14 +---
 .../customizableui/CustomizableWidgets.jsm    | 18 +++++
 .../components/customizableui/test/head.js    |  5 ++
 .../components/preferences/in-content/main.js | 75 ++++++++++++++++++-
 .../preferences/in-content/main.xul           | 18 +++++
 .../locales/en-US/chrome/browser/browser.dtd  |  1 +
 .../customizableWidgets.properties            |  3 +
 .../en-US/chrome/browser/preferences/main.dtd |  2 +
 .../themes/shared/toolbarbutton-icons.inc.css |  8 ++
 devtools/client/locales/en-US/performance.dtd |  5 ++
 .../performance/performance-controller.js     | 18 +++--
 devtools/client/performance/performance.xul   |  4 +
 .../test/browser_perf-recording-notices-05.js | 22 +++++-
 devtools/client/themes/performance.css        |  4 +-
 moz.configure                                 | 11 +++
 toolkit/modules/AppConstants.jsm              |  7 ++
 21 files changed, 264 insertions(+), 29 deletions(-)

diff --git a/browser/base/content/browser-menubar.inc b/browser/base/content/browser-menubar.inc
index e818cdfafcbe..6dc75f7547fe 100644
--- a/browser/base/content/browser-menubar.inc
+++ b/browser/base/content/browser-menubar.inc
@@ -34,6 +34,12 @@
                           accesskey="&newPrivateWindow.accesskey;"
                           command="Tools:PrivateBrowsing"
                           key="key_privatebrowsing"/>
+#ifdef E10S_TESTING_ONLY
+                <menuitem id="menu_newNonRemoteWindow"
+                          label="&newNonRemoteWindow.label;"
+                          hidden="true"
+                          command="Tools:NonRemoteWindow"/>
+#endif
 #ifdef MAC_NON_BROWSER_WINDOW
                 <menuitem id="menu_openLocation"
                           label="&openLocationCmd.label;"
diff --git a/browser/base/content/browser-sets.inc b/browser/base/content/browser-sets.inc
index b353313cd07b..49be3820199c 100644
--- a/browser/base/content/browser-sets.inc
+++ b/browser/base/content/browser-sets.inc
@@ -102,6 +102,10 @@
      oncommand="Cc['@mozilla.org/browser/browserglue;1'].getService(Ci.nsIBrowserGlue).sanitize(window);"/>
     <command id="Tools:PrivateBrowsing"
       oncommand="OpenBrowserWindow({private: true});"/>
+#ifdef E10S_TESTING_ONLY
+    <command id="Tools:NonRemoteWindow"
+      oncommand="OpenBrowserWindow({remote: false});"/>
+#endif
     <command id="History:UndoCloseTab" oncommand="undoCloseTab();"/>
     <command id="History:UndoCloseWindow" oncommand="undoCloseWindow();"/>
   </commandset>
diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 12a03b01616c..8831891dc375 100755
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -1466,6 +1466,9 @@ var gBrowserInit = {
     IndexedDBPromptHelper.init();
     CanvasPermissionPromptHelper.init();
 
+    if (AppConstants.E10S_TESTING_ONLY)
+      gRemoteTabsUI.init();
+
     // Initialize the full zoom setting.
     // We do this before the session restore service gets initialized so we can
     // apply full zoom settings to tabs restored by the session restore service.
@@ -1979,6 +1982,9 @@ if (AppConstants.platform == "macosx") {
     // initialize the private browsing UI
     gPrivateBrowsingUI.init();
 
+    if (AppConstants.E10S_TESTING_ONLY) {
+      gRemoteTabsUI.init();
+    }
   };
 
   gBrowserInit.nonBrowserWindowShutdown = function() {
@@ -8277,6 +8283,27 @@ var gPrivateBrowsingUI = {
   }
 };
 
+var gRemoteTabsUI = {
+  init() {
+    if (window.location.href != getBrowserURL() &&
+        // Also check hidden window for the Mac no-window case
+        window.location.href != "chrome://browser/content/hiddenWindow.xul") {
+      return;
+    }
+
+    if (AppConstants.platform == "macosx" &&
+        Services.prefs.getBoolPref("layers.acceleration.disabled")) {
+      // On OS X, "Disable Hardware Acceleration" also disables OMTC and forces
+      // a fallback to Basic Layers. This is incompatible with e10s.
+      return;
+    }
+
+    let newNonRemoteWindow = document.getElementById("menu_newNonRemoteWindow");
+    let autostart = Services.appinfo.browserTabsRemoteAutostart;
+    newNonRemoteWindow.hidden = !autostart;
+  }
+};
+
 /**
  * Switch to a tab that has a given URI, and focuses its browser window.
  * If a matching tab is in this window, it will be switched to. Otherwise, other
@@ -8534,6 +8561,16 @@ var TabContextMenu = {
     if (this.contextTab.hasAttribute("customizemode"))
       document.getElementById("context_openTabInWindow").disabled = true;
 
+    if (AppConstants.E10S_TESTING_ONLY) {
+      menuItems = aPopupMenu.getElementsByAttribute("tbattr", "tabbrowser-remote");
+      for (let menuItem of menuItems) {
+        menuItem.hidden = !gMultiProcessBrowser;
+        if (menuItem.id == "context_openNonRemoteWindow") {
+          menuItem.disabled = !!parseInt(this.contextTab.getAttribute("usercontextid"));
+        }
+      }
+    }
+
     disabled = gBrowser.visibleTabs.length == 1;
     menuItems = aPopupMenu.getElementsByAttribute("tbattr", "tabbrowser-multiple-visible");
     for (let menuItem of menuItems)
diff --git a/browser/base/content/browser.xul b/browser/base/content/browser.xul
index 3058058ab390..206575daa5c6 100644
--- a/browser/base/content/browser.xul
+++ b/browser/base/content/browser.xul
@@ -96,6 +96,12 @@
                 accesskey="&moveToNewWindow.accesskey;"
                 tbattr="tabbrowser-multiple"
                 oncommand="gBrowser.replaceTabWithWindow(TabContextMenu.contextTab);"/>
+#ifdef E10S_TESTING_ONLY
+      <menuitem id="context_openNonRemoteWindow" label="Open in new non-e10s window"
+                tbattr="tabbrowser-remote"
+                hidden="true"
+                oncommand="gBrowser.openNonRemoteWindow(TabContextMenu.contextTab);"/>
+#endif
       <menuseparator id="context_sendTabToDevice_separator"/>
       <menu id="context_sendTabToDevice" label="&sendTabToDevice.label;"
             accesskey="&sendTabToDevice.accesskey;">
diff --git a/browser/base/content/tabbrowser.xml b/browser/base/content/tabbrowser.xml
index e14f5955d253..df1e479d677b 100644
--- a/browser/base/content/tabbrowser.xml
+++ b/browser/base/content/tabbrowser.xml
@@ -3954,6 +3954,20 @@
         </body>
       </method>
 
+      <!-- Opens a given tab to a non-remote window. -->
+      <method name="openNonRemoteWindow">
+        <parameter name="aTab"/>
+        <body>
+          <![CDATA[
+            if (!AppConstants.E10S_TESTING_ONLY) {
+              throw "This method is intended only for e10s testing!";
+            }
+            let url = aTab.linkedBrowser.currentURI.spec;
+            return window.openDialog("chrome://browser/content/", "_blank", "chrome,all,dialog=no,non-remote", url);
+          ]]>
+        </body>
+      </method>
+
       <method name="moveTabTo">
         <parameter name="aTab"/>
         <parameter name="aIndex"/>
@@ -5530,11 +5544,14 @@
             }
           } else {
             label = tab._fullLabel || tab.getAttribute("label");
-            if (AppConstants.NIGHTLY_BUILD &&
+            if (AppConstants.E10S_TESTING_ONLY &&
                 tab.linkedBrowser &&
-                tab.linkedBrowser.isRemoteBrowser &&
-                tab.linkedBrowser.frameLoader) {
-              label += " (pid " + tab.linkedBrowser.frameLoader.tabParent.osPid + ")";
+                tab.linkedBrowser.isRemoteBrowser) {
+              label += " - e10s";
+              if (tab.linkedBrowser.frameLoader &&
+                  Services.appinfo.maxWebProcessCount > 1) {
+                label += " (" + tab.linkedBrowser.frameLoader.tabParent.osPid + ")";
+              }
             }
             if (tab.userContextId) {
               label = this.mStringBundle.getFormattedString("tabs.containers.tooltip", [label, ContextualIdentityService.getUserContextLabel(tab.userContextId)]);
diff --git a/browser/components/customizableui/CustomizableUI.jsm b/browser/components/customizableui/CustomizableUI.jsm
index 81dd963122b9..de20ffe7e87c 100644
--- a/browser/components/customizableui/CustomizableUI.jsm
+++ b/browser/components/customizableui/CustomizableUI.jsm
@@ -59,7 +59,7 @@ const kSubviewEvents = [
  * The current version. We can use this to auto-add new default widgets as necessary.
  * (would be const but isn't because of testing purposes)
  */
-var kVersion = 13;
+var kVersion = 12;
 
 /**
  * Buttons removed from built-ins by version they were removed. kVersion must be
@@ -345,6 +345,7 @@ var CustomizableUIInternal = {
         "preferences-button",
         "add-ons-button",
         "sync-button",
+        "e10s-button",
       ];
 
       if (!AppConstants.MOZ_DEV_EDITION) {
@@ -451,17 +452,6 @@ var CustomizableUIInternal = {
         }
       }
     }
-
-    // Remove the old placements from the now-gone Nightly-only
-    // "New non-e10s window" button.
-    if (currentVersion < 13 && gSavedState.placements) {
-      for (let placements of Object.values(gSavedState.placements)) {
-        let buttonIndex = placements.indexOf("e10s-button");
-        if (buttonIndex != -1) {
-          placements.spice(buttonIndex, 1);
-        }
-      }
-    }
   },
 
   /**
diff --git a/browser/components/customizableui/CustomizableWidgets.jsm b/browser/components/customizableui/CustomizableWidgets.jsm
index 936cf374b3aa..4ce4f7baf077 100644
--- a/browser/components/customizableui/CustomizableWidgets.jsm
+++ b/browser/components/customizableui/CustomizableWidgets.jsm
@@ -997,3 +997,21 @@ if (Services.prefs.getBoolPref("privacy.panicButton.enabled")) {
     },
   });
 }
+
+if (AppConstants.E10S_TESTING_ONLY) {
+  if (Services.appinfo.browserTabsRemoteAutostart) {
+    CustomizableWidgets.push({
+      id: "e10s-button",
+      defaultArea: CustomizableUI.AREA_PANEL,
+      onBuild(aDocument) {
+        let node = aDocument.createElementNS(kNSXUL, "toolbarbutton");
+        node.setAttribute("label", CustomizableUI.getLocalizedProperty(this, "label"));
+        node.setAttribute("tooltiptext", CustomizableUI.getLocalizedProperty(this, "tooltiptext"));
+      },
+      onCommand(aEvent) {
+        let win = aEvent.view;
+        win.OpenBrowserWindow({remote: false});
+      },
+    });
+  }
+}
diff --git a/browser/components/customizableui/test/head.js b/browser/components/customizableui/test/head.js
index c4faea4e02c0..5267dcf2da21 100644
--- a/browser/components/customizableui/test/head.js
+++ b/browser/components/customizableui/test/head.js
@@ -17,6 +17,11 @@ Services.scriptloader.loadSubScript("chrome://mochikit/content/tests/SimpleTest/
 Services.prefs.setBoolPref("browser.uiCustomization.skipSourceNodeCheck", true);
 registerCleanupFunction(() => Services.prefs.clearUserPref("browser.uiCustomization.skipSourceNodeCheck"));
 
+// Remove temporary e10s related new window options in customize ui,
+// they break a lot of tests.
+CustomizableUI.destroyWidget("e10s-button");
+CustomizableUI.removeWidgetFromArea("e10s-button");
+
 var {synthesizeDragStart, synthesizeDrop} = EventUtils;
 
 const kNSXUL = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
diff --git a/browser/components/preferences/in-content/main.js b/browser/components/preferences/in-content/main.js
index 92f3f649056c..696ee6b69e92 100644
--- a/browser/components/preferences/in-content/main.js
+++ b/browser/components/preferences/in-content/main.js
@@ -97,6 +97,11 @@ const APP_ICON_ATTR_NAME = "appHandlerIcon";
 XPCOMUtils.defineLazyModuleGetter(this, "OS",
   "resource://gre/modules/osfile.jsm");
 
+if (AppConstants.E10S_TESTING_ONLY) {
+  XPCOMUtils.defineLazyModuleGetter(this, "UpdateUtils",
+    "resource://gre/modules/UpdateUtils.jsm");
+}
+
 if (AppConstants.MOZ_DEV_EDITION) {
   XPCOMUtils.defineLazyModuleGetter(this, "fxAccounts",
     "resource://gre/modules/FxAccounts.jsm");
@@ -314,6 +319,26 @@ var gMainPane = {
       }
     }
 
+    if (AppConstants.E10S_TESTING_ONLY) {
+      setEventListener("e10sAutoStart", "command",
+        gMainPane.enableE10SChange);
+      let e10sCheckbox = document.getElementById("e10sAutoStart");
+
+      let e10sPref = document.getElementById("browser.tabs.remote.autostart");
+      let e10sTempPref = document.getElementById("e10sTempPref");
+      let e10sForceEnable = document.getElementById("e10sForceEnable");
+
+      let preffedOn = e10sPref.value || e10sTempPref.value || e10sForceEnable.value;
+
+      if (preffedOn) {
+        // The checkbox is checked if e10s is preffed on and enabled.
+        e10sCheckbox.checked = Services.appinfo.browserTabsRemoteAutostart;
+
+        // but if it's force disabled, then the checkbox is disabled.
+        e10sCheckbox.disabled = !Services.appinfo.browserTabsRemoteAutostart;
+      }
+    }
+
     if (AppConstants.MOZ_DEV_EDITION) {
       let uAppData = OS.Constants.Path.userApplicationDataDir;
       let ignoreSeparateProfile = OS.Path.join(uAppData, "ignore-dev-edition-profile");
@@ -521,6 +546,54 @@ var gMainPane = {
     this.readBrowserContainersCheckbox();
   },
 
+  isE10SEnabled() {
+    let e10sEnabled;
+    try {
+      let e10sStatus = Components.classes["@mozilla.org/supports-PRUint64;1"]
+        .createInstance(Ci.nsISupportsPRUint64);
+      let appinfo = Services.appinfo.QueryInterface(Ci.nsIObserver);
+      appinfo.observe(e10sStatus, "getE10SBlocked", "");
+      e10sEnabled = e10sStatus.data < 2;
+    } catch (e) {
+      e10sEnabled = false;
+    }
+
+    return e10sEnabled;
+  },
+
+  enableE10SChange() {
+    if (AppConstants.E10S_TESTING_ONLY) {
+      let e10sCheckbox = document.getElementById("e10sAutoStart");
+      let e10sPref = document.getElementById("browser.tabs.remote.autostart");
+      let e10sTempPref = document.getElementById("e10sTempPref");
+
+      let prefsToChange;
+      if (e10sCheckbox.checked) {
+        // Enabling e10s autostart
+        prefsToChange = [e10sPref];
+      } else {
+        // Disabling e10s autostart
+        prefsToChange = [e10sPref];
+        if (e10sTempPref.value) {
+          prefsToChange.push(e10sTempPref);
+        }
+      }
+
+      let buttonIndex = confirmRestartPrompt(e10sCheckbox.checked, 0,
+        true, false);
+      if (buttonIndex == CONFIRM_RESTART_PROMPT_RESTART_NOW) {
+        for (let prefToChange of prefsToChange) {
+          prefToChange.value = e10sCheckbox.checked;
+        }
+
+        Services.startup.quit(Ci.nsIAppStartup.eAttemptQuit | Ci.nsIAppStartup.eRestart);
+      }
+
+      // Revert the checkbox in case we didn't quit
+      e10sCheckbox.checked = e10sPref.value || e10sTempPref.value;
+    }
+  },
+
   separateProfileModeChange() {
     if (AppConstants.MOZ_DEV_EDITION) {
       function quitApp() {
@@ -1212,7 +1285,7 @@ var gMainPane = {
   },
 
   buildContentProcessCountMenuList() {
-    if (Services.appinfo.browserTabsRemoteAutostart) {
+    if (gMainPane.isE10SEnabled()) {
       let processCountPref = document.getElementById("dom.ipc.processCount");
       let e10sRolloutProcessCountPref =
         document.getElementById("dom.ipc.processCount.web");
diff --git a/browser/components/preferences/in-content/main.xul b/browser/components/preferences/in-content/main.xul
index 64fa7366814f..92c896b458fc 100644
--- a/browser/components/preferences/in-content/main.xul
+++ b/browser/components/preferences/in-content/main.xul
@@ -17,6 +17,19 @@
 <stringbundle id="bundlePreferences" src="chrome://browser/locale/preferences.properties"/>
 
 <preferences id="mainPreferences" hidden="true" data-category="paneGeneral">
+
+#ifdef E10S_TESTING_ONLY
+    <preference id="browser.tabs.remote.autostart"
+                name="browser.tabs.remote.autostart"
+                type="bool"/>
+    <preference id="e10sTempPref"
+                name="browser.tabs.remote.autostart.2"
+                type="bool"/>
+    <preference id="e10sForceEnable"
+                name="browser.tabs.remote.force-enable"
+                type="bool"/>
+#endif
+
     <!-- Startup -->
     <preference id="browser.startup.page"
                 name="browser.startup.page"
@@ -285,6 +298,11 @@
   </vbox>
 #endif
 
+#ifdef E10S_TESTING_ONLY
+  <checkbox id="e10sAutoStart"
+            label="&e10sEnabled.label;"/>
+#endif
+
 #ifdef HAVE_SHELL_SERVICE
   <vbox id="defaultBrowserBox">
     <checkbox id="alwaysCheckDefault" preference="browser.shell.checkDefaultBrowser"
diff --git a/browser/locales/en-US/chrome/browser/browser.dtd b/browser/locales/en-US/chrome/browser/browser.dtd
index 1103f042a06d..dfbaeaba44cd 100644
--- a/browser/locales/en-US/chrome/browser/browser.dtd
+++ b/browser/locales/en-US/chrome/browser/browser.dtd
@@ -294,6 +294,7 @@ These should match what Safari and other Apple applications use on OS X Lion. --
 <!ENTITY newNavigatorCmd.accesskey      "N">
 <!ENTITY newPrivateWindow.label     "New Private Window">
 <!ENTITY newPrivateWindow.accesskey "W">
+<!ENTITY newNonRemoteWindow.label   "New Non-e10s Window">
 
 <!ENTITY editMenu.label         "Edit">
 <!ENTITY editMenu.accesskey       "E">
diff --git a/browser/locales/en-US/chrome/browser/customizableui/customizableWidgets.properties b/browser/locales/en-US/chrome/browser/customizableui/customizableWidgets.properties
index 762068a1688b..84403c3ef53a 100644
--- a/browser/locales/en-US/chrome/browser/customizableui/customizableWidgets.properties
+++ b/browser/locales/en-US/chrome/browser/customizableui/customizableWidgets.properties
@@ -101,6 +101,9 @@ panic-button.tooltiptext = Forget about some browsing history
 devtools-webide-button2.label = WebIDE
 devtools-webide-button2.tooltiptext = Open WebIDE (%S)
 
+e10s-button.label = New Non-e10s Window
+e10s-button.tooltiptext = Open a new Non-e10s Window
+
 toolbarspring.label = Flexible Space
 toolbarseparator.label = Separator
 toolbarspacer.label = Space
diff --git a/browser/locales/en-US/chrome/browser/preferences/main.dtd b/browser/locales/en-US/chrome/browser/preferences/main.dtd
index cf5c569ed6ea..924f6f2fd14e 100644
--- a/browser/locales/en-US/chrome/browser/preferences/main.dtd
+++ b/browser/locales/en-US/chrome/browser/preferences/main.dtd
@@ -44,3 +44,5 @@
 <!ENTITY useFirefoxSync.label             "Tip: This uses separate profiles. Use Sync to share data between them.">
 <!ENTITY getStarted.notloggedin.label     "Sign in to &syncBrand.shortName.label;…">
 <!ENTITY getStarted.configured.label      "Open &syncBrand.shortName.label; preferences">
+
+<!ENTITY e10sEnabled.label                "Enable multi-process &brandShortName;">
diff --git a/browser/themes/shared/toolbarbutton-icons.inc.css b/browser/themes/shared/toolbarbutton-icons.inc.css
index d1e672db7f46..9ee2107c3397 100644
--- a/browser/themes/shared/toolbarbutton-icons.inc.css
+++ b/browser/themes/shared/toolbarbutton-icons.inc.css
@@ -229,6 +229,14 @@ toolbar[brighttext] {
   list-style-image: url("chrome://browser/skin/new-window.svg");
 }
 
+#e10s-button {
+  list-style-image: url("chrome://browser/skin/new-window.svg");
+}
+
+#e10s-button > .toolbarbutton-icon {
+  transform: scaleY(-1);
+}
+
 #new-tab-button {
   list-style-image: url("chrome://browser/skin/new-tab.svg");
 }
diff --git a/devtools/client/locales/en-US/performance.dtd b/devtools/client/locales/en-US/performance.dtd
index 5b5c1eda045a..4009ae10450f 100644
--- a/devtools/client/locales/en-US/performance.dtd
+++ b/devtools/client/locales/en-US/performance.dtd
@@ -15,6 +15,11 @@
   -  is displayed as the tooltip for the buffer capacity during a recording. -->
 <!ENTITY performanceUI.bufferStatusTooltip "The profiler stores samples in a circular buffer, and once the buffer reaches the limit for a recording, newer samples begin to overwrite samples at the beginning of the recording.">
 
+<!-- LOCALIZATION NOTE (performanceUI.disabledRealTime.nonE10SBuild): This string
+  -  is displayed as a message for why the real time overview graph is disabled
+  -  when running on a non-multiprocess build. -->
+<!ENTITY performanceUI.disabledRealTime.nonE10SBuild "Realtime recording data disabled on non-multiprocess Firefox.">
+
 <!-- LOCALIZATION NOTE (performanceUI.disabledRealTime.disabledE10S): This string
   -  is displayed as a message for why the real time overview graph is disabled
   -  when running on a build that can run multiprocess Firefox, but just is not enabled. -->
diff --git a/devtools/client/performance/performance-controller.js b/devtools/client/performance/performance-controller.js
index bf53c248b024..5d2724acec8a 100644
--- a/devtools/client/performance/performance-controller.js
+++ b/devtools/client/performance/performance-controller.js
@@ -517,17 +517,18 @@ var PerformanceController = {
    * @return {object}
    */
   getMultiprocessStatus: function () {
-    // If testing, set enabled to true so we have realtime rendering tests
-    // in non-e10s. This function is overridden wholesale in tests
-    // when we want to test multiprocess support
+    // If testing, set both supported and enabled to true so we
+    // have realtime rendering tests in non-e10s. This function is
+    // overridden wholesale in tests when we want to test multiprocess support
     // specifically.
     if (flags.testing) {
-      return { enabled: true };
+      return { supported: true, enabled: true };
     }
+    let supported = system.constants.E10S_TESTING_ONLY;
     // This is only checked on tool startup -- requires a restart if
     // e10s subsequently enabled.
     let enabled = this._e10s;
-    return { enabled };
+    return { supported, enabled };
   },
 
   /**
@@ -555,9 +556,12 @@ var PerformanceController = {
    * if e10s is not possible on the platform. If e10s is on, no attribute is set.
    */
   _setMultiprocessAttributes: function () {
-    let { enabled } = this.getMultiprocessStatus();
-    if (!enabled) {
+    let { enabled, supported } = this.getMultiprocessStatus();
+    if (!enabled && supported) {
       $("#performance-view").setAttribute("e10s", "disabled");
+    } else if (!enabled && !supported) {
+      // Could be a chance where the directive goes away yet e10s is still on
+      $("#performance-view").setAttribute("e10s", "unsupported");
     }
   },
 
diff --git a/devtools/client/performance/performance.xul b/devtools/client/performance/performance.xul
index effbc8f8b8d0..7ceb41c84851 100644
--- a/devtools/client/performance/performance.xul
+++ b/devtools/client/performance/performance.xul
@@ -211,6 +211,8 @@
               <hbox pack="center">
                 <html:div class='recording-button-mount'/>
               </hbox>
+              <label class="realtime-disabled-message"
+                     value="&performanceUI.disabledRealTime.nonE10SBuild;"/>
               <label class="realtime-disabled-on-e10s-message"
                      value="&performanceUI.disabledRealTime.disabledE10S;"/>
               <label class="buffer-status-message"
@@ -235,6 +237,8 @@
                 <label class="console-profile-command" />
                 <label value="&performanceUI.console.stopCommandEnd;" />
               </hbox>
+              <label class="realtime-disabled-message"
+                     value="&performanceUI.disabledRealTime.nonE10SBuild;"/>
               <label class="realtime-disabled-on-e10s-message"
                      value="&performanceUI.disabledRealTime.disabledE10S;"/>
               <label class="buffer-status-message"
diff --git a/devtools/client/performance/test/browser_perf-recording-notices-05.js b/devtools/client/performance/test/browser_perf-recording-notices-05.js
index 5107f81a6bad..b6267470d19f 100644
--- a/devtools/client/performance/test/browser_perf-recording-notices-05.js
+++ b/devtools/client/performance/test/browser_perf-recording-notices-05.js
@@ -20,21 +20,35 @@ add_task(function* () {
   // Set a fast profiler-status update interval
   yield gFront.setProfilerStatusInterval(10);
 
+  let supported = false;
   let enabled = false;
 
   PerformanceController.getMultiprocessStatus = () => {
-    return { enabled };
+    return { supported, enabled };
   };
 
+  PerformanceController._setMultiprocessAttributes();
+  ok($("#performance-view").getAttribute("e10s"), "unsupported",
+    "When e10s is disabled and no option to turn on, container has [e10s=unsupported].");
+
+  supported = true;
+  enabled = false;
   PerformanceController._setMultiprocessAttributes();
   ok($("#performance-view").getAttribute("e10s"), "disabled",
-    "When e10s is disabled, container has [e10s=disabled].");
+    "When e10s is disabled and but is supported, container has [e10s=disabled].");
 
+  supported = false;
   enabled = true;
-
   PerformanceController._setMultiprocessAttributes();
   ok($("#performance-view").getAttribute("e10s"), "",
-    "When e10s is enabled, there should be no e10s attribute.");
+    "When e10s is enabled, but not supported, this probably means we no longer have " +
+    "E10S_TESTING_ONLY, and we have no e10s attribute.");
+
+  supported = true;
+  enabled = true;
+  PerformanceController._setMultiprocessAttributes();
+  ok($("#performance-view").getAttribute("e10s"), "",
+    "When e10s is enabled and supported, there should be no e10s attribute.");
 
   yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/themes/performance.css b/devtools/client/themes/performance.css
index 794a1a267d9d..28887dc25f98 100644
--- a/devtools/client/themes/performance.css
+++ b/devtools/client/themes/performance.css
@@ -247,11 +247,13 @@
   margin: 3px 2px;
 }
 
+.realtime-disabled-message,
 .realtime-disabled-on-e10s-message {
   display: none;
 }
 
-#performance-view[e10s="disabled"] .realtime-disabled-on-e10s-message {
+#performance-view[e10s="disabled"] .realtime-disabled-on-e10s-message,
+#performance-view[e10s="unsupported"] .realtime-disabled-message {
   display: initial;
   opacity: 0.5;
 }
diff --git a/moz.configure b/moz.configure
index da81abffb532..4ea93b7a3d15 100755
--- a/moz.configure
+++ b/moz.configure
@@ -14,6 +14,17 @@ include('build/moz.configure/init.configure')
 # - Spidermonkey-specific options and rules should go in js/moz.configure.
 # - etc.
 
+# Multiprocess Firefox Testing UI - Nightly and Aurora
+# To be removed in Bug 1003313
+@depends(milestone)
+def e10s_testing_only(milestone):
+    if not milestone.is_release_or_beta:
+        return True
+
+set_config('E10S_TESTING_ONLY', e10s_testing_only)
+set_define('E10S_TESTING_ONLY', e10s_testing_only)
+
+
 option('--enable-artifact-builds', env='MOZ_ARTIFACT_BUILDS',
        help='Download and use prebuilt binary artifacts.')
 
diff --git a/toolkit/modules/AppConstants.jsm b/toolkit/modules/AppConstants.jsm
index 327f5e796958..db6176d95b47 100644
--- a/toolkit/modules/AppConstants.jsm
+++ b/toolkit/modules/AppConstants.jsm
@@ -180,6 +180,13 @@ this.AppConstants = Object.freeze({
   false,
 #endif
 
+  E10S_TESTING_ONLY:
+#ifdef E10S_TESTING_ONLY
+  true,
+#else
+  false,
+#endif
+
   DEBUG:
 #ifdef DEBUG
   true,