Remove WebLayerTreeView::finishAllRendering(), nothing uses it.

public/platform/WebLayerTreeView.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 110 matching lines @@
 
     // Run layout and paint of all pending document changes asynchronously.
     // The caller is resposible for keeping the WebLayoutAndPaintAsyncCallback object
     // alive until it is called.
     virtual void layoutAndPaintAsync(WebLayoutAndPaintAsyncCallback*) { }
 
     // The caller is responsible for keeping the WebCompositeAndReadbackAsyncCallback
     // object alive until it is called.
     virtual void compositeAndReadbackAsync(WebCompositeAndReadbackAsyncCallback*) { }
 
-    // Blocks until the most recently composited frame has finished rendering on the GPU.
-    // This can have a significant performance impact and should be used with care.
-    virtual void finishAllRendering() { }
-
     // Prevents updates to layer tree from becoming visible.
     virtual void setDeferCommits(bool deferCommits) { }
 
     // Take responsiblity for this layer's animations, even if this layer hasn't yet
     // been added to the tree.
     virtual void registerForAnimations(WebLayer* layer) { }
 
     // Identify key layers to the compositor when using the pinch virtual viewport.
     virtual void registerViewportLayers(
         const WebLayer* overscrollElasticityLayer,
@@ skipping 24 matching lines @@
     // Toggles continuous painting
     virtual void setContinuousPaintingEnabled(bool) { }
 
     // Toggles scroll bottleneck rects on the HUD layer
     virtual void setShowScrollBottleneckRects(bool) { }
 };
 
 } // namespace blink
 
 #endif // WebLayerTreeView_h