Mac ÜC: Enable GPU back-pressure from the browser to the renderer

content/browser/renderer_host/render_widget_host_view_mac.h

Index: content/browser/renderer_host/render_widget_host_view_mac.h
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.h b/content/browser/renderer_host/render_widget_host_view_mac.h
index 5380fa73d24e74e1e84aef066d42a5f8a0905c10..181784138bb9a7defcdf01ac1dfa009623742ccc 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -16,6 +16,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
+#include "content/browser/compositor/browser_compositor_view_mac.h"
 #include "content/browser/compositor/delegated_frame_host.h"
 #include "content/browser/renderer_host/compositing_iosurface_layer_mac.h"
 #include "content/browser/renderer_host/display_link_mac.h"
@@ -213,6 +214,7 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
       public DelegatedFrameHostClient,
       public IPC::Sender,
       public SoftwareFrameManagerClient,
+      public BrowserCompositorViewMacClient,
       public CompositingIOSurfaceLayerClient {
  public:
   // The view will associate itself with the given widget. The native view must
@@ -343,6 +345,9 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
 
   virtual SkBitmap::Config PreferredReadbackFormat() OVERRIDE;
 
+  // BrowserCompositorViewMacHelper implementation.
+  virtual void BrowserCompositorDidDrawFrame() OVERRIDE;
+
   // CompositingIOSurfaceLayerClient implementation.
   virtual void AcceleratedLayerDidDrawFrame(bool succeeded) OVERRIDE;
 
@@ -448,6 +453,12 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   scoped_ptr<DelegatedFrameHost> delegated_frame_host_;
   scoped_ptr<ui::Layer> root_layer_;
 
+  // This lock is taken when the browser compositor produces a frame, and is
+  // released when that frame is displayed. It is by this mechanism that the
+  // browser compositor can exert GPU backpressure on the renderer compositor.
+  scoped_refptr<ui::CompositorLock> browser_compositor_lock_;
+  bool browser_compositor_damaged_during_lock_;
+
   // This holds the current software compositing framebuffer, if any.
   scoped_ptr<SoftwareFrameManager> software_frame_manager_;
 
@@ -518,6 +529,8 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   virtual RenderWidgetHostImpl* GetHost() OVERRIDE;
   virtual void SchedulePaintInRect(
       const gfx::Rect& damage_rect_in_dip) OVERRIDE;
+  virtual void DelegatedCompositorDidSwapBuffers() OVERRIDE;
+  virtual void DelegatedCompositorAbortedSwapBuffers() OVERRIDE;
   virtual bool IsVisible() OVERRIDE;
   virtual scoped_ptr<ResizeLock> CreateResizeLock(
       bool defer_compositor_lock) OVERRIDE;
@@ -590,6 +603,12 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   // Send updated vsync parameters to the renderer.
   void SendVSyncParametersToRenderer();
 
+  // Release the browser compositor lock, and request another frame from the
+  // browser compositor. Because this can be requested from inside compositor
+  // calbacks, post it as task instead of calling it directly.
+  void PostReleaseBrowserCompositorLock();
+  void ReleaseBrowserCompositorLock();
+
   // The associated view. This is weak and is inserted into the view hierarchy
   // to own this RenderWidgetHostViewMac object. Set to nil at the start of the
   // destructor.