b=763449 Finish X requests on mROFrontBuffer before deleting shadow layer r=cjones

--HG--
extra : rebase_source : 7381b234a29d648afdf76eff1f1e89f6e5cd88b5

gfx/layers/basic/BasicThebesLayer.cpp

@@ -281,6 +281,17 @@ private:
   AutoBufferTracker& operator=(const AutoBufferTracker&) MOZ_DELETE;
 };
 
+BasicShadowableThebesLayer::~BasicShadowableThebesLayer()
+{
+  // Finish any use of mROFrontBuffer since the last ForwardTransaction(),
+  // before the Shadow frees the surface.
+  if (OptionalThebesBuffer::Tnull_t != mROFrontBuffer.type()) {
+    ShadowLayerForwarder::PlatformSyncBeforeUpdate();
+  }
+  DestroyBackBuffer();
+  MOZ_COUNT_DTOR(BasicShadowableThebesLayer);
+}
+
 void
 BasicShadowableThebesLayer::PaintThebes(gfxContext* aContext,
                                         Layer* aMaskLayer,

gfx/layers/basic/BasicThebesLayer.h

@@ -121,11 +121,7 @@ public:
   {
     MOZ_COUNT_CTOR(BasicShadowableThebesLayer);
   }
-  virtual ~BasicShadowableThebesLayer()
-  {
-    DestroyBackBuffer();
-    MOZ_COUNT_DTOR(BasicShadowableThebesLayer);
-  }
+  virtual ~BasicShadowableThebesLayer();
 
   virtual void PaintThebes(gfxContext* aContext,
                            Layer* aMaskLayer,

gfx/layers/ipc/ShadowLayerUtilsX11.cpp

@@ -177,7 +177,7 @@ ShadowLayerForwarder::PlatformSyncBeforeUpdate()
     // operations on the back buffers before handing them to the
     // parent, otherwise the surface might be used by the parent's
     // Display in between two operations queued by our Display.
-    XSync(DefaultXDisplay(), False);
+    FinishX(DefaultXDisplay());
   }
 }
 

gfx/layers/ipc/ShadowLayers.h

@@ -319,6 +319,8 @@ public:
   virtual int32_t GetMaxTextureSize() const { return mMaxTextureSize; }
   void SetMaxTextureSize(int32_t aMaxTextureSize) { mMaxTextureSize = aMaxTextureSize; }
 
+  static void PlatformSyncBeforeUpdate();
+
 protected:
   ShadowLayerForwarder();
 
@@ -379,8 +381,6 @@ private:
 
   bool PlatformDestroySharedSurface(SurfaceDescriptor* aSurface);
 
-  static void PlatformSyncBeforeUpdate();
-
   Transaction* mTxn;
   int32_t mMaxTextureSize;
   LayersBackend mParentBackend;