Unified BeginFrame scheduling

ui/compositor/compositor.h

Index: ui/compositor/compositor.h
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index b2d27797de7fc1af7938ba330d02eb39f891cbc5..5c390366519d16d5f9386e5aa4653fa0c7d28e58 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -30,6 +30,7 @@ class RunLoop;
 }
 
 namespace cc {
+class BeginFrameManager;
 class ContextProvider;
 class Layer;
 class LayerTreeDebugState;
@@ -49,7 +50,6 @@ struct Mailbox;
 namespace ui {
 
 class Compositor;
-class CompositorVSyncManager;
 class Layer;
 class Reflector;
 class Texture;
@@ -184,8 +184,12 @@ class COMPOSITOR_EXPORT Compositor
   // Returns the widget for this compositor.
   gfx::AcceleratedWidget widget() const { return widget_; }
 
-  // Returns the vsync manager for this compositor.
-  scoped_refptr<CompositorVSyncManager> vsync_manager() const;
+  // See cc::BeginFrameManager::Delegate comment.
+  void SetAuthoritativeVSyncInterval(base::TimeDelta interval) const;
+
+  cc::BeginFrameManager* begin_frame_manager() const {

[brianderson, 2014/08/28 02:48:07]

Instead of exposing the BeginFrameManager to everyone, I think it would be
cleaner to only expose it through forwarding methods instead.

[simonhong, 2014/09/03 21:02:23]

BeginFrameManager is removed.
Instead, {Add|Remove}BeginFrameObserver() is added and will be used
by RWHV.

+    return begin_frame_manager_.get();
+  }
 
   // Compositor does not own observers. It is the responsibility of the
   // observer to remove itself when it is done observing.
@@ -267,8 +271,8 @@ class COMPOSITOR_EXPORT Compositor
   scoped_refptr<base::MessageLoopProxy> compositor_thread_loop_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
-  // The manager of vsync parameters for this compositor.
-  scoped_refptr<CompositorVSyncManager> vsync_manager_;
+  // The manager of BeginFrame routing.
+  scoped_ptr<cc::BeginFrameManager> begin_frame_manager_;

[brianderson, 2014/08/28 02:48:07]

Would it make sense for the LTH or Proxy to own the BeginFrameManager instead? I
don't think all platforms use ui::Compositor.

[simonhong, 2014/08/29 00:03:01]

My plan was making BeginFrameManager as a member variable of each
compositor(ui::Compositor and CompositorImpl).
After seeing your this and above comment, each compositor only needs to have
BeginFrameObserver that manage RWHV.
After removing BeginFrameManager, current BeginFrameManger::Delegate's api
should
move into LTH. Then, only interaction between compositor and LTH is needed.
With this, we don't need to expose Scheduler to compositor as you said and all
requests
(ex, SetChildrenNeedsBeginFrame, authoritative, StartBeginFrame) will be
delivered to scheduler
only through LTH. (StartBeginFrame will be used to call scheduler's BeginFrame()
when vsync is triggered on Mac and Android)
What do you think about this change?

 
   // The device scale factor of the monitor that this compositor is compositing
   // layers on.