cc: Plumbing for BeginFrameSource based on Surfaces

cc/surfaces/display.h

Index: cc/surfaces/display.h
diff --git a/cc/surfaces/display.h b/cc/surfaces/display.h
index b849b461afb69bbf506b9a330635e8e3edc7d171..3873d133cec14b1da355b57734e51d36d9d627fe 100644
--- a/cc/surfaces/display.h
+++ b/cc/surfaces/display.h
@@ -11,6 +11,7 @@
 #include "cc/output/output_surface_client.h"
 #include "cc/output/renderer.h"
 #include "cc/resources/returned_resource.h"
+#include "cc/scheduler/begin_frame_source.h"
 #include "cc/surfaces/display_scheduler.h"
 #include "cc/surfaces/surface_aggregator.h"
 #include "cc/surfaces/surface_id.h"
@@ -28,6 +29,7 @@ class Size;
 
 namespace cc {
 
+class BeginFrameSource;
 class DirectRenderer;
 class DisplayClient;
 class OutputSurface;
@@ -46,6 +48,7 @@ class TextureMailboxDeleter;
 class CC_SURFACES_EXPORT Display : public DisplaySchedulerClient,
                                    public OutputSurfaceClient,
                                    public RendererClient,
+                                   public SurfaceAggregatorClient,
                                    public SurfaceDamageObserver {
  public:
   Display(DisplayClient* client,
@@ -66,6 +69,10 @@ class CC_SURFACES_EXPORT Display : public DisplaySchedulerClient,
 
   SurfaceId CurrentSurfaceId();
 
+  // SurfaceAggregatorClient implementation
+  void AddSurface(Surface* surface) override;
+  void RemoveSurface(Surface* surface) override;
+
   // DisplaySchedulerClient implementation.
   bool DrawAndSwap() override;