Bug 722012 - Added a call to XInitThreads before the first call to XOpenDisplay to fix OMTC crashes. r=karlt

--HG--
rename : toolkit/mozapps/update/test/chrome/test_0093_stagedBackground.xul => toolkit/mozapps/update/test/chrome/test_0092_finishedBackground.xul
rename : toolkit/mozapps/update/test/unit/test_0113_general.js => toolkit/mozapps/update/test/unit/test_0110_general.js
rename : toolkit/mozapps/update/test/unit/test_0114_general.js => toolkit/mozapps/update/test/unit/test_0111_general.js
rename : toolkit/mozapps/update/test/unit/test_0115_general.js => toolkit/mozapps/update/test/unit/test_0112_general.js
rename : toolkit/mozapps/update/test/unit/test_0172_fileLocked_xp_win_complete.js => toolkit/mozapps/update/test/unit/test_0170_fileLocked_xp_win_complete.js
rename : toolkit/mozapps/update/test_svc/unit/test_0173_fileLocked_xp_win_partial_svc.js => toolkit/mozapps/update/test/unit/test_0171_fileLocked_xp_win_partial.js
extra : rebase_source : f527614c4a5f0b8979bd8bc39dcd3ca739ba9e08

modules/libpref/src/init/all.js

@@ -3434,7 +3434,13 @@ pref("layers.acceleration.force-enabled", false);
 
 pref("layers.acceleration.draw-fps", false);
 
+// An environment variable (MOZ_USE_OMTC)is used instead of a pref on X11 
+// platforms because we start having access to prefs long after the first 
+// call to XOpenDisplay which is hard to change due to interdependencies 
+// in the initialization (see bug 722012 for more details).
+#ifndef MOZ_X11
 pref("layers.offmainthreadcomposition.enabled", false);
+#endif
 
 #ifdef MOZ_X11
 #ifdef MOZ_WIDGET_GTK2

toolkit/xre/nsAppRunner.cpp

@@ -3267,7 +3267,18 @@ XREMain::XRE_mainStartup(bool* aExitFlag)
       return 1;
   }
 #endif
-
+#ifdef MOZ_X11
+  // Init X11 in thread-safe mode. Must be called prior to the first call to XOpenDisplay 
+  // (called inside gdk_display_open). This is a requirement for off main tread compositing.
+  // This is done only on X11 platforms if the environment variable MOZ_USE_OMTC is set so 
+  // as to avoid overhead when omtc is not used. 
+  // An environment variable is used instead of a pref on X11 platforms because we start having 
+  // access to prefs long after the first call to XOpenDisplay which is hard to change due to 
+  // interdependencies in the initialization.
+  if (PR_GetEnv("MOZ_USE_OMTC")) {
+    XInitThreads();
+  }
+#endif
 #if defined(MOZ_WIDGET_GTK2)
   mGdkDisplay = gdk_display_open(display_name);
   if (!mGdkDisplay) {

widget/android/nsWindow.cpp

@@ -692,8 +692,7 @@ nsWindow::GetLayerManager(PLayersChild*, LayersBackend, LayerManagerPersistence,
         return mLayerManager;
     }
 #ifdef MOZ_JAVA_COMPOSITOR
-    bool useCompositor =
-        Preferences::GetBool("layers.offmainthreadcomposition.enabled", false);
+    bool useCompositor = UseOffMainThreadCompositing();
 
     if (useCompositor) {
         CreateCompositor();

widget/gonk/nsWindow.cpp

@@ -128,7 +128,7 @@ nsWindow::nsWindow()
             NS_RUNTIMEABORT("Failed to create framebufferWatcherThread, aborting...");
         }
 
-        sUsingOMTC = Preferences::GetBool("layers.offmainthreadcomposition.enabled", false);
+        sUsingOMTC = UseOffMainThreadCompositing();
 
         // We (apparently) don't have a way to tell if allocating the
         // fbs succeeded or failed.

widget/xpwidgets/nsBaseWidget.cpp

@@ -25,6 +25,7 @@
 #include "nsIGfxInfo.h"
 #include "npapi.h"
 #include "base/thread.h"
+#include "prenv.h"
 
 #ifdef DEBUG
 #include "nsIObserver.h"
@@ -38,6 +39,9 @@ static bool debug_InSecureKeyboardInputMode = false;
 static PRInt32 gNumWidgets;
 #endif
 
+static void InitOnlyOnce();
+static bool sUseOffMainThreadCompositing = false;
+
 using namespace mozilla::layers;
 using namespace mozilla;
 using base::Thread;
@@ -100,8 +104,9 @@ nsBaseWidget::nsBaseWidget()
 #endif
 
 #ifdef DEBUG
-    debug_RegisterPrefCallbacks();
+  debug_RegisterPrefCallbacks();
 #endif
+  InitOnlyOnce();
 }
 
 
@@ -889,6 +894,11 @@ void nsBaseWidget::CreateCompositor()
   }
 }
 
+bool nsBaseWidget::UseOffMainThreadCompositing()
+{
+  return sUseOffMainThreadCompositing;
+}
+
 LayerManager* nsBaseWidget::GetLayerManager(PLayersChild* aShadowManager,
                                             LayersBackend aBackendHint,
                                             LayerManagerPersistence aPersistence,
@@ -901,9 +911,7 @@ LayerManager* nsBaseWidget::GetLayerManager(PLayersChild* aShadowManager,
     if (mUseAcceleratedRendering) {
 
       // Try to use an async compositor first, if possible
-      bool useCompositor =
-        Preferences::GetBool("layers.offmainthreadcomposition.enabled", false);
-      if (useCompositor) {
+      if (UseOffMainThreadCompositing()) {
         // e10s uses the parameter to pass in the shadow manager from the TabChild
         // so we don't expect to see it there since this doesn't support e10s.
         NS_ASSERTION(aShadowManager == nsnull, "Async Compositor not supported with e10s");
@@ -1303,6 +1311,25 @@ nsBaseWidget::GetGLFrameBufferFormat()
   return LOCAL_GL_NONE;
 }
 
+static void InitOnlyOnce()
+{
+  static bool once = true;
+  if (!once) {
+    return;
+  }
+  once = false;
+
+#ifdef MOZ_X11
+  // On X11 platforms only use OMTC if firefox was initalized with thread-safe 
+  // X11 (else it would crash).
+  sUseOffMainThreadCompositing = (PR_GetEnv("MOZ_USE_OMTC") != NULL);
+#else
+  sUseOffMainThreadCompositing = mozilla::Preferences::GetBool(
+        "layers.offmainthreadcomposition.enabled", 
+        false);
+#endif
+}
+
 #ifdef DEBUG
 //////////////////////////////////////////////////////////////
 //

widget/xpwidgets/nsBaseWidget.h

@@ -209,6 +209,7 @@ public:
 
   nsWindowType            GetWindowType() { return mWindowType; }
 
+  static bool             UseOffMainThreadCompositing();
 protected:
 
   virtual void            ResolveIconName(const nsAString &aIconName,