[WIP] cc: Plumb SurfaceId from clients

ui/compositor/compositor.h

Index: ui/compositor/compositor.h
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index ee39c5943659e8f49eebe333bde230ea1ff3f9ac..de70465aede438bd8eada1d564a28dd905bda451 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -129,8 +129,7 @@ class COMPOSITOR_EXPORT ContextFactory {
   virtual cc::TaskGraphRunner* GetTaskGraphRunner() = 0;
 
   // Creates a Surface ID allocator with a new namespace.
-  virtual std::unique_ptr<cc::SurfaceIdAllocator>
-  CreateSurfaceIdAllocator() = 0;
+  virtual uint32_t AllocateSurfaceClientId() = 0;
 
   // Gets the surface manager.
   virtual cc::SurfaceManager* GetSurfaceManager() = 0;
@@ -194,6 +193,8 @@ class COMPOSITOR_EXPORT Compositor
 
   ui::ContextFactory* context_factory() { return context_factory_; }
 
+  bool initialized() const { return initialized_; }
+
   void SetOutputSurface(std::unique_ptr<cc::OutputSurface> surface);
 
   // Schedules a redraw of the layer tree associated with this compositor.
@@ -374,6 +375,7 @@ class COMPOSITOR_EXPORT Compositor
   base::ObserverList<CompositorObserver, true> observer_list_;
   base::ObserverList<CompositorAnimationObserver> animation_observer_list_;
 
+  bool initialized_;
   gfx::AcceleratedWidget widget_;
   bool widget_valid_;
   bool output_surface_requested_;