Mozart: Generalize frame scheduling.

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";
+import "mojo/services/gfx/composition/interfaces/scheduling.mojom";
 
 // The renderer is a service which renders a scene graph to a display.
 //
 // Use |Compositor.CreateRenderer()| to create a renderer.
 interface Renderer {
   // Sets the scene to be displayed by the renderer.
   //
   // The |size| specifies the size of the output.
   //
   // The |scene_token| specifies the scene which will be drawn as the
   // root of the scene graph.
   //
   // The |scene_version| specifies the version of the scene to render,
   // Use |kSceneVersionNone| to request the most recently published
   // version of the scene if synchronization is unimportant.
   //
   // The |viewport| specifies the portion of the scene to render in pixels.
   //
   // 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.
   ClearRootScene();
 
+  // Gets a scheduler to receive frame timing information for the renderer.
+  GetScheduler(FrameScheduler& scheduler);
+
   // Provides an interface which can be used to perform hit tests on the
   // contents of the renderer's scene graph.
   GetHitTester(HitTester& hit_tester);
 };