Hook up ui::Compositor to Display's BeginFrameSource

cc/surfaces/display_scheduler.h

Index: cc/surfaces/display_scheduler.h
diff --git a/cc/surfaces/display_scheduler.h b/cc/surfaces/display_scheduler.h
index 90e99f4344a3662e730850b6d217c81369f0a89f..af48fbf16e915a25fc1f29de46d22eae4ddc58da 100644
--- a/cc/surfaces/display_scheduler.h
+++ b/cc/surfaces/display_scheduler.h
@@ -10,6 +10,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/single_thread_task_runner.h"
+#include "cc/output/renderer_settings.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surfaces_export.h"
@@ -24,6 +25,7 @@ class CC_SURFACES_EXPORT DisplaySchedulerClient {
   virtual ~DisplaySchedulerClient() {}
 
   virtual bool DrawAndSwap() = 0;
+  virtual void UpdateSchedulerBeginFrameSource(BeginFrameSource* source) = 0;
 };
 
 class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
@@ -31,7 +33,8 @@ class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
   DisplayScheduler(DisplaySchedulerClient* client,
                    BeginFrameSource* begin_frame_source,
                    base::SingleThreadTaskRunner* task_runner,
-                   int max_pending_swaps);
+                   int max_pending_swaps,
+                   const RendererSettings& settings);
   ~DisplayScheduler() override;
 
   void SetRootSurfaceResourcesLocked(bool locked);
@@ -49,10 +52,6 @@ class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
   bool OnBeginFrameDerivedImpl(const BeginFrameArgs& args) override;
   void OnBeginFrameSourcePausedChanged(bool paused) override;
 
-  BeginFrameSource* begin_frame_source_for_children() {
-    return begin_frame_source_for_children_.get();
-  }
-
  protected:
   base::TimeTicks DesiredBeginFrameDeadlineTime();
   virtual void ScheduleBeginFrameDeadline();
@@ -69,8 +68,7 @@ class CC_SURFACES_EXPORT DisplayScheduler : public BeginFrameObserverBase {
   base::CancelableClosure begin_frame_deadline_task_;
   base::TimeTicks begin_frame_deadline_task_time_;
 
-  // TODO(tansell): Set this to something useful.
-  scoped_ptr<BeginFrameSource> begin_frame_source_for_children_;
+  scoped_ptr<BeginFrameSource> unthrottled_begin_frame_source_;
 
   bool output_surface_lost_;
   bool root_surface_resources_locked_;