Let every "accelerated IO surface swapped" message have an identifier of the surface.

app/surface/accelerated_surface_mac.h

Index: app/surface/accelerated_surface_mac.h
diff --git a/app/surface/accelerated_surface_mac.h b/app/surface/accelerated_surface_mac.h
index a111c1438255840959bb592c48d1c682438fb29b..a43effa50b8e082b2ed93d3449f1fd1d47ec5de0 100644
--- a/app/surface/accelerated_surface_mac.h
+++ b/app/surface/accelerated_surface_mac.h
@@ -58,6 +58,10 @@ class AcceleratedSurface {
   // occurred. MakeCurrent() will have been called on the new surface.
   uint64 SetSurfaceSize(const gfx::Size& size);
 
+  // Returns the id of this surface's IOSruface, or 0 for
+  // transport DIB surfaces.
+  uint64 GetSurfaceId();
+
   // Sets the GL context to be the current one for drawing. Returns true if
   // it succeeded.
   bool MakeCurrent();
@@ -131,6 +135,10 @@ class AcceleratedSurface {
   // TODO(dspringer,kbr): Should the GPU backing store be encapsulated in its
   // own class so all this implementation detail is hidden?
   base::mac::ScopedCFTypeRef<CFTypeRef> io_surface_;
+
+  // The id of |io_surface_| or 0 if that's NULL.
+  uint64 io_surface_id_;
+
   // TODO(dspringer): If we end up keeping this TransportDIB mechanism, this
   // should really be a scoped_ptr_malloc<>, with a deallocate functor that
   // runs |dib_free_callback_|.  I was not able to figure out how to