Mozart: Directly associate the renderer with the view tree.

mojo/services/gfx/composition/interfaces/renderers.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [DartPackage="mojo_services"]
 module mojo.gfx.composition;
 
 import "mojo/services/geometry/interfaces/geometry.mojom";
 import "mojo/services/gfx/composition/interfaces/hit_tests.mojom";
 import "mojo/services/gfx/composition/interfaces/scene_token.mojom";
@@ skipping 14 matching lines @@
   // version of the scene if synchronization is unimportant.
   //
   // The |viewport| specifies the portion of the scene to render.
   //
   // It is an error to create a renderer with an invalid |scene_token|
   // or |size|; the connection will be closed.
   // TODO: make this an event instead
   SetRootScene(SceneToken scene_token, uint32 scene_version,
     mojo.Rect viewport);
 
+  // Dissociates the root scene from the renderer.
+  ResetRootScene();

[abarth, 2016/03/09 03:48:41]

ClearRootScene?  We've sort of vaguely been following the naming conventions in
the C++ standard library.

+
   // Provides an interface which can be used to perform hit tests on the
   // contents of the renderer's scene graph.
   GetHitTester(HitTester& hit_tester);
 };