cc: Make separate interface for BeginFrame ipc from OutputSurface

ui/compositor/compositor.cc

Index: ui/compositor/compositor.cc
diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index 4d07e1ee1d0c31001fd5aea5f39da6fe87217315..ccc759c7423638ec82cc0677b42b4f4334c94005 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -20,6 +20,7 @@
 #include "cc/layers/layer.h"
 #include "cc/output/begin_frame_args.h"
 #include "cc/output/context_provider.h"
+#include "cc/scheduler/begin_frame_source.h"
 #include "cc/surfaces/surface_id_allocator.h"
 #include "cc/trees/layer_tree_host.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ -65,8 +66,6 @@ void CompositorLock::CancelLock() {
 
 }  // namespace ui
 
-namespace {}  // namespace
-
 namespace ui {
 
 class SatisfySwapPromise : public cc::SwapPromise {
@@ -164,14 +163,16 @@ Compositor::Compositor(gfx::AcceleratedWidget widget,
         context_factory_->GetSharedBitmapManager(),
         settings,
         task_runner_,
-        compositor_thread_loop_);
+        compositor_thread_loop_,
+        scoped_ptr<cc::ExternalBeginFrameSource>());
   } else {
     host_ = cc::LayerTreeHost::CreateSingleThreaded(
         this,
         this,
         context_factory_->GetSharedBitmapManager(),
         settings,
-        task_runner_);
+        task_runner_,
+        scoped_ptr<cc::ExternalBeginFrameSource>());
   }
   UMA_HISTOGRAM_TIMES("GPU.CreateBrowserCompositor",
                       base::TimeTicks::Now() - before_create);