cc: Plumbing for BeginFrameSource based on Surfaces

cc/surfaces/surface_factory.cc

Index: cc/surfaces/surface_factory.cc
diff --git a/cc/surfaces/surface_factory.cc b/cc/surfaces/surface_factory.cc
index 3e83c8cfd7341c57485af26fbcc9873e8b2beb51..6cc9d4938cecd2e4e14ca15325d73455cee418fa 100644
--- a/cc/surfaces/surface_factory.cc
+++ b/cc/surfaces/surface_factory.cc
@@ -8,6 +8,7 @@
 #include "cc/output/compositor_frame.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/surfaces/surface.h"
+#include "cc/surfaces/surface_factory_client.h"
 #include "cc/surfaces/surface_manager.h"
 #include "ui/gfx/geometry/size.h"
 
@@ -26,6 +27,7 @@ SurfaceFactory::~SurfaceFactory() {
                << " entries in map on destruction.";
   }
   DestroyAll();
+  client_->SetBeginFrameSource(nullptr);
 }
 
 void SurfaceFactory::DestroyAll() {
@@ -39,6 +41,7 @@ void SurfaceFactory::Create(SurfaceId surface_id) {
   manager_->RegisterSurface(surface.get());
   DCHECK(!surface_map_.count(surface_id));
   surface_map_.add(surface_id, surface.Pass());
+  most_recently_created_surface_id_ = surface_id;
 }
 
 void SurfaceFactory::Destroy(SurfaceId surface_id) {
@@ -48,6 +51,14 @@ void SurfaceFactory::Destroy(SurfaceId surface_id) {
   manager_->Destroy(surface_map_.take_and_erase(it));
 }
 
+void SurfaceFactory::SetBeginFrameSource(SurfaceId surface_id,
+                                         BeginFrameSource* begin_frame_source) {
+  if (most_recently_created_surface_id_ != surface_id)

[mithro-old, 2015/10/01 03:00:24]

nit: Can you add a comment about why this check is needed?

[brianderson, 2015/10/07 20:54:48]

Done.

+    return;
+
+  client_->SetBeginFrameSource(begin_frame_source);
+}
+
 void SurfaceFactory::SubmitCompositorFrame(SurfaceId surface_id,
                                            scoped_ptr<CompositorFrame> frame,
                                            const DrawCallback& callback) {