From 09597e239131046e8de53779b19b4fb9be906be1 Mon Sep 17 00:00:00 2001
From: Oleg Romashin <romaxa@gmail.com>
Date: Sun, 16 Dec 2012 11:25:04 -0800
Subject: [PATCH] Bug 822115 - nglayout.debug.widget_update_flashing pref cache
 is not thread safe. r=mattwoodrow

---
 gfx/layers/basic/BasicLayerManager.cpp | 11 +----------
 gfx/thebes/gfxPlatform.cpp             |  3 +++
 gfx/thebes/gfxPlatform.h               |  3 +++
 3 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/gfx/layers/basic/BasicLayerManager.cpp b/gfx/layers/basic/BasicLayerManager.cpp
index 290af04d2d40..ca13ba773e60 100644
--- a/gfx/layers/basic/BasicLayerManager.cpp
+++ b/gfx/layers/basic/BasicLayerManager.cpp
@@ -629,16 +629,7 @@ BasicLayerManager::EndTransactionInternal(DrawThebesLayerCallback aCallback,
 void
 BasicLayerManager::FlashWidgetUpdateArea(gfxContext *aContext)
 {
-  static bool sWidgetFlashingEnabled;
-  static bool sWidgetFlashingPrefCached = false;
-
-  if (!sWidgetFlashingPrefCached) {
-    sWidgetFlashingPrefCached = true;
-    mozilla::Preferences::AddBoolVarCache(&sWidgetFlashingEnabled,
-                                          "nglayout.debug.widget_update_flashing");
-  }
-
-  if (sWidgetFlashingEnabled) {
+  if (gfxPlatform::GetPlatform()->WidgetUpdateFlashing()) {
     float r = float(rand()) / RAND_MAX;
     float g = float(rand()) / RAND_MAX;
     float b = float(rand()) / RAND_MAX;
diff --git a/gfx/thebes/gfxPlatform.cpp b/gfx/thebes/gfxPlatform.cpp
index 952053e3e6a3..2f5c52e02a75 100644
--- a/gfx/thebes/gfxPlatform.cpp
+++ b/gfx/thebes/gfxPlatform.cpp
@@ -340,6 +340,9 @@ gfxPlatform::Init()
 
     gPlatform->mWorkAroundDriverBugs = Preferences::GetBool("gfx.work-around-driver-bugs", true);
 
+    mozilla::Preferences::AddBoolVarCache(&gPlatform->mWidgetUpdateFlashing,
+                                          "nglayout.debug.widget_update_flashing");
+
     mozilla::gl::GLContext::PlatformStartup();
 
 #ifdef MOZ_WIDGET_ANDROID
diff --git a/gfx/thebes/gfxPlatform.h b/gfx/thebes/gfxPlatform.h
index 6db40f796939..99badcf7b4dd 100644
--- a/gfx/thebes/gfxPlatform.h
+++ b/gfx/thebes/gfxPlatform.h
@@ -493,6 +493,8 @@ public:
 
     virtual int GetScreenDepth() const;
 
+    bool WidgetUpdateFlashing() const { return mWidgetUpdateFlashing; }
+
 protected:
     gfxPlatform();
     virtual ~gfxPlatform();
@@ -586,6 +588,7 @@ private:
     bool mWorkAroundDriverBugs;
 
     mozilla::RefPtr<mozilla::gfx::DrawEventRecorder> mRecorder;
+    bool mWidgetUpdateFlashing;
 };
 
 #endif /* GFX_PLATFORM_H */