Bug 1356119 - Skip Flush to old context after device reset. r=dvander

gfx/layers/Compositor.h

@@ -418,7 +418,7 @@ public:
    */
   virtual void EndFrame();
 
-  virtual void CancelFrame() { ReadUnlockTextures(); }
+  virtual void CancelFrame(bool aNeedFlush = true) { ReadUnlockTextures(); }
 
   virtual void SetDispAcquireFence(Layer* aLayer);
 

gfx/layers/composite/LayerManagerComposite.cpp

@@ -1369,7 +1369,7 @@ void
 LayerManagerComposite::ChangeCompositor(Compositor* aNewCompositor)
 {
   if (mCompositor) {
-    mCompositor->CancelFrame();
+    mCompositor->CancelFrame(false);
   }
   mCompositor = aNewCompositor;
   mTwoPassTmpTarget = nullptr;

gfx/layers/d3d11/CompositorD3D11.cpp

@@ -1534,12 +1534,14 @@ CompositorD3D11::Present()
 }
 
 void
-CompositorD3D11::CancelFrame()
+CompositorD3D11::CancelFrame(bool aNeedFlush)
 {
   ReadUnlockTextures();
   // Flush the context, otherwise the driver might hold some resources alive
   // until the next flush or present.
-  mContext->Flush();
+  if (aNeedFlush) {
+    mContext->Flush();
+  }
 }
 
 void

gfx/layers/d3d11/CompositorD3D11.h

@@ -119,7 +119,7 @@ public:
    */
   virtual void EndFrame() override;
 
-  virtual void CancelFrame() override;
+  virtual void CancelFrame(bool aNeedFlush = true) override;
 
   /**
    * Setup the viewport and projection matrix for rendering