Don't access mCompositor from CompositeToTarget. (bug 1339688 part 2, r=mattwoodrow)

gfx/layers/composite/LayerManagerComposite.cpp

@@ -1410,6 +1410,12 @@ LayerManagerComposite::AsyncPanZoomEnabled() const
   return false;
 }
 
+bool
+LayerManagerComposite::AlwaysScheduleComposite() const
+{
+  return !!(mCompositor->GetDiagnosticTypes() & DiagnosticTypes::FLASH_BORDERS);
+}
+
 nsIntRegion
 LayerComposite::GetFullyRenderedRegion() {
   if (TiledContentHost* tiled = GetCompositableHost() ? GetCompositableHost()->AsTiledContentHost()

gfx/layers/composite/LayerManagerComposite.h

@@ -164,6 +164,10 @@ public:
 
   void SetPaintTime(const TimeDuration& aPaintTime) { mLastPaintTime = aPaintTime; }
 
+  virtual bool AlwaysScheduleComposite() const {
+    return false;
+  }
+
   TimeStamp GetCompositionTime() const {
     return mCompositionTime;
   }
@@ -279,6 +283,8 @@ public:
 
   virtual const char* Name() const override { return ""; }
 
+  bool AlwaysScheduleComposite() const override;
+
   /**
    * Post-processes layers before composition. This performs the following:
    *

gfx/layers/ipc/CompositorBridgeParent.cpp

@@ -1034,8 +1034,9 @@ CompositorBridgeParent::CompositeToTarget(DrawTarget* aTarget, const gfx::IntRec
 #endif
 
   // 0 -> Full-tilt composite
-  if (gfxPrefs::LayersCompositionFrameRate() == 0
-    || mLayerManager->GetCompositor()->GetDiagnosticTypes() & DiagnosticTypes::FLASH_BORDERS) {
+  if (gfxPrefs::LayersCompositionFrameRate() == 0 ||
+      mLayerManager->AlwaysScheduleComposite())
+  {
     // Special full-tilt composite mode for performance testing
     ScheduleComposition();
   }