RenderWidget's scheduleComposite should return a bool. (true iff a prompt composite will come).

ui/gfx/compositor/compositor.h

 // Copyright (c) 2012 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 UI_GFX_COMPOSITOR_COMPOSITOR_H_
 #define UI_GFX_COMPOSITOR_COMPOSITOR_H_
 #pragma once
 
 #include "base/hash_tables.h"
 #include "base/memory/ref_counted.h"
@@ skipping 192 matching lines @@
 
   // WebLayerTreeViewClient implementation.
   virtual void updateAnimations(double frameBeginTime);
   virtual void layout();
   virtual void applyScrollAndScale(const WebKit::WebSize& scrollDelta,
                                    float scaleFactor);
   virtual WebKit::WebGraphicsContext3D* createContext3D();
   virtual void didRebindGraphicsContext(bool success);
   virtual void didCommitAndDrawFrame();
   virtual void didCompleteSwapBuffers();
+
+#if defined(WEBLAYERTREEVIEWCLIENT_SCHEDULECOMPOSITE_RETURNS_BOOL)
+  virtual bool scheduleComposite();
+#else
   virtual void scheduleComposite();
+#endif
 
  private:
   // When reading back pixel data we often get RGBA rather than BGRA pixels and
   // and the image often needs to be flipped vertically.
   static void SwizzleRGBAToBGRAAndFlip(unsigned char* pixels,
                                        const gfx::Size& image_size);
 
   // Notifies the compositor that compositing is complete.
   void NotifyEnd();
 
@@ skipping 12 matching lines @@
   // This is set to true when the swap buffers has been posted and we're waiting
   // for completion.
   bool swap_posted_;
 
   friend class base::RefCounted<Compositor>;
 };
 
 }  // namespace ui
 
 #endif  // UI_GFX_COMPOSITOR_COMPOSITOR_H_