Make software compositing work on Mac.

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 11b1d973a42a88d49ce55080c73135e43280546c..a398f70e4b7f9fa3acbf832954639c668bb0c45b 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -18,6 +18,7 @@
 #include "base/time/time.h"
 #include "content/browser/accessibility/browser_accessibility_delegate_mac.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
+#include "content/browser/renderer_host/software_framebuffer.h"
 #include "content/common/edit_command.h"
 #import "content/public/browser/render_widget_host_view_mac_base.h"
 #include "ipc/ipc_sender.h"
@@ -196,6 +197,7 @@ class RenderWidgetHostImpl;
 //
 // RenderWidgetHostView class hierarchy described in render_widget_host_view.h.
 class RenderWidgetHostViewMac : public RenderWidgetHostViewBase,
+                                public SoftwareFramebufferClient,
                                 public IPC::Sender {
  public:
   virtual ~RenderWidgetHostViewMac();
@@ -283,6 +285,9 @@ class RenderWidgetHostViewMac : public RenderWidgetHostViewBase,
   virtual void BeginFrameSubscription(
       scoped_ptr<RenderWidgetHostViewFrameSubscriber> subscriber) OVERRIDE;
   virtual void EndFrameSubscription() OVERRIDE;
+  virtual void OnSwapCompositorFrame(
+      uint32 output_surface_id,
+      scoped_ptr<cc::CompositorFrame> frame) OVERRIDE;
   virtual void OnAcceleratedCompositingStateChange() OVERRIDE;
   virtual void OnAccessibilityEvents(
       const std::vector<AccessibilityHostMsg_EventParams>& params
@@ -313,6 +318,9 @@ class RenderWidgetHostViewMac : public RenderWidgetHostViewBase,
   virtual void UnhandledWheelEvent(
       const WebKit::WebMouseWheelEvent& event) OVERRIDE;
 
+  // SoftwareFramebufferClient implementation.
+  virtual void CurrentSoftwareFrameWasDiscarded() OVERRIDE {}
+
   // IPC::Sender implementation.
   virtual bool Send(IPC::Message* message) OVERRIDE;
 
@@ -412,6 +420,9 @@ class RenderWidgetHostViewMac : public RenderWidgetHostViewBase,
   scoped_ptr<CompositingIOSurfaceMac> compositing_iosurface_;
   scoped_refptr<CompositingIOSurfaceContext> compositing_iosurface_context_;
 
+  // Framebuffer for software compositing.
+  scoped_ptr<SoftwareFramebuffer> software_framebuffer_;
+
   // Whether to allow overlapping views.
   bool allow_overlapping_views_;