Use swap-promise to improve first* paint times

content/renderer/gpu/render_widget_compositor.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_GPU_RENDER_WIDGET_COMPOSITOR_H_
 #define CONTENT_RENDERER_GPU_RENDER_WIDGET_COMPOSITOR_H_
 
 #include <stdint.h>
 
 #include "base/callback.h"
@@ skipping 35 matching lines @@
 
 namespace content {
 
 class RenderWidgetCompositorDelegate;
 struct ScreenInfo;
 
 class CONTENT_EXPORT RenderWidgetCompositor
     : NON_EXPORTED_BASE(public blink::WebLayerTreeView),
       NON_EXPORTED_BASE(public cc::LayerTreeHostClient),
       NON_EXPORTED_BASE(public cc::LayerTreeHostSingleThreadClient) {
+  using ReportTimeCallback = base::Callback<void(bool, double)>;
+
  public:
   // Attempt to construct and initialize a compositor instance for the widget
   // with the given settings. Returns NULL if initialization fails.
   static std::unique_ptr<RenderWidgetCompositor> Create(
       RenderWidgetCompositorDelegate* delegate,
       CompositorDependencies* compositor_deps);
 
   ~RenderWidgetCompositor() override;
 
   static cc::LayerTreeSettings GenerateLayerTreeSettings(
@@ skipping 94 matching lines @@
   void UpdateEventRectsForSubframeIfNecessary() override;
   blink::WebEventListenerProperties EventListenerProperties(
       blink::WebEventListenerClass eventClass) const override;
   void SetHaveScrollEventHandlers(bool) override;
   bool HaveScrollEventHandlers() const override;
   int LayerTreeId() const override;
   void SetShowFPSCounter(bool show) override;
   void SetShowPaintRects(bool show) override;
   void SetShowDebugBorders(bool show) override;
   void SetShowScrollBottleneckRects(bool show) override;
+  void NotifySwapTime(ReportTimeCallback callback) override;
 
   void UpdateBrowserControlsState(blink::WebBrowserControlsState constraints,
                                   blink::WebBrowserControlsState current,
                                   bool animate) override;
   void SetBrowserControlsHeight(float height, bool shrink) override;
   void SetBrowserControlsShownRatio(float) override;
   // TODO(ianwen): Move this method to WebLayerTreeView and implement main
   // thread scrolling.
   virtual void setBottomControlsHeight(float height);
 
@@ skipping 53 matching lines @@
   std::unique_ptr<cc::AnimationHost> animation_host_;
   std::unique_ptr<cc::LayerTreeHost> layer_tree_host_;
   bool never_visible_;
   bool is_for_oopif_;
 
   blink::WebLayoutAndPaintAsyncCallback* layout_and_paint_async_callback_;
 
   cc::FrameSinkId frame_sink_id_;
 
   base::WeakPtrFactory<RenderWidgetCompositor> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderWidgetCompositor);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_GPU_RENDER_WIDGET_COMPOSITOR_H_