[WIP] cc: Plumb SurfaceId from clients

ui/compositor/compositor.cc

Index: ui/compositor/compositor.cc
diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index b217cddc5028a4f0e3813a2e6ff461599f9eee22..49733ad488b78e33de11a9cdfcf8c549c8036d6b 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -79,10 +79,12 @@ Compositor::Compositor(ui::ContextFactory* context_factory,
                        scoped_refptr<base::SingleThreadTaskRunner> task_runner)
     : context_factory_(context_factory),
       root_layer_(NULL),
+      initialized_(false),
       widget_(gfx::kNullAcceleratedWidget),
       widget_valid_(false),
       output_surface_requested_(false),
-      surface_id_allocator_(context_factory->CreateSurfaceIdAllocator()),
+      surface_id_allocator_(base::WrapUnique(new cc::SurfaceIdAllocator(
+          context_factory->AllocateSurfaceClientId()))),
       task_runner_(task_runner),
       vsync_manager_(new CompositorVSyncManager()),
       device_scale_factor_(0.0f),
@@ -429,6 +431,9 @@ void Compositor::RequestNewOutputSurface() {
 }
 
 void Compositor::DidInitializeOutputSurface() {
+  initialized_ = true;
+  FOR_EACH_OBSERVER(CompositorObserver, observer_list_,
+                    OnCompositingInitialized(this));
 }
 
 void Compositor::DidFailToInitializeOutputSurface() {