Use swap-promise to improve first* paint times

third_party/WebKit/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 15 matching lines @@
 #ifndef WebLayerTreeView_h
 #define WebLayerTreeView_h
 
 #include "WebBrowserControlsState.h"
 #include "WebColor.h"
 #include "WebCommon.h"
 #include "WebCompositorMutatorClient.h"
 #include "WebEventListenerProperties.h"
 #include "WebFloatPoint.h"
 #include "WebSize.h"
+#include "base/callback.h"
 #include "cc/surfaces/frame_sink_id.h"
 
 namespace cc {
 class AnimationHost;
 }
 
 namespace blink {
 
 class WebCompositeAndReadbackAsyncCallback;
 class WebLayer;
 class WebLayoutAndPaintAsyncCallback;
 struct WebPoint;
 class WebSelection;
 
 class WebLayerTreeView {
+  using ReportTimeCallback = base::Callback<void(bool, double)>;
+
  public:
   virtual ~WebLayerTreeView() {}
 
   // Initialization and lifecycle --------------------------------------
 
   // Sets the root of the tree. The root is set by way of the constructor.
   virtual void SetRootLayer(const WebLayer&) {}
   virtual void ClearRootLayer() {}
 
   // TODO(loyso): This should use CompositorAnimationHost. crbug.com/584551
@@ skipping 113 matching lines @@
   virtual void SetShowFPSCounter(bool) {}
 
   // Toggles the paint rects in the HUD layer
   virtual void SetShowPaintRects(bool) {}
 
   // Toggles the debug borders on layers
   virtual void SetShowDebugBorders(bool) {}
 
   // Toggles scroll bottleneck rects on the HUD layer
   virtual void SetShowScrollBottleneckRects(bool) {}
+
+  // ReportTimeCallback is a callback that should be fired when the
+  // corresponding Swap completes (either with DidSwap or DidNotSwap).
+  virtual void NotifySwapTime(ReportTimeCallback callback) {}
 };
 
 }  // namespace blink
 
 #endif  // WebLayerTreeView_h