Dynamically set CAOpenGLLAyer to be asynchronous

content/browser/renderer_host/compositing_iosurface_layer_mac.h

 // Copyright 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_BROWSER_RENDERER_HOST_COMPOSITING_IOSURFACE_LAYER_MAC_H_
 #define CONTENT_BROWSER_RENDERER_HOST_COMPOSITING_IOSURFACE_LAYER_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/ref_counted.h"
 
 namespace content {
 class CompositingIOSurfaceContext;
 class RenderWidgetHostViewMac;
 }
 
 // The CoreAnimation layer for drawing accelerated content.
 @interface CompositingIOSurfaceLayer : CAOpenGLLayer {
  @private
   content::RenderWidgetHostViewMac* renderWidgetHostView_;
   scoped_refptr<content::CompositingIOSurfaceContext> context_;
+
+  // Used to track when canDrawInCGLContext should return YES. This can be
+  // in response to receiving a new compositor frame, or from any of the events
+  // that cause setNeedsDisplay to be called on the layer.
+  BOOL needsDisplay_;
 }
 
 @property(nonatomic, readonly)
     scoped_refptr<content::CompositingIOSurfaceContext> context;
 
 - (id)initWithRenderWidgetHostViewMac:(content::RenderWidgetHostViewMac*)r;
 
 // Update the scale factor of the layer to match the scale factor of the
 // IOSurface.
 - (void)updateScaleFactor;
 
 // Remove this layer from the layer heirarchy, and mark that
 // |renderWidgetHostView_| is no longer valid and may no longer be dereferenced.
 - (void)disableCompositing;
 
+// Called when a new frame is received.
+- (void)gotNewFrame;
+
+// Called when it has been a while since a new frame has been received, and the
+// layer should become not-asynchronous.
+- (void)timerSinceGotNewFrameFired;
+
 @end
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_COMPOSITING_IOSURFACE_LAYER_MAC_H_