Convert offscreen canvas to use FrameSinkManagerHost.

third_party/WebKit/public/platform/modules/offscreencanvas/offscreen_canvas_surface.mojom

 // Copyright 2016 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.
 
 module blink.mojom;
 
 import "cc/ipc/compositor_frame.mojom";
 import "cc/ipc/display_compositor.mojom";
 import "cc/ipc/frame_sink_id.mojom";
 import "cc/ipc/mojo_compositor_frame_sink.mojom";
 import "cc/ipc/surface_id.mojom";
 import "cc/ipc/surface_sequence.mojom";
 
 interface OffscreenCanvasSurface {
   Require(cc.mojom.SurfaceId surface_id, cc.mojom.SurfaceSequence sequence);
   Satisfy(cc.mojom.SurfaceSequence sequence);
 };
 
-interface OffscreenCanvasSurfaceFactory {
+// Creates OffscreenCanvasSurface and MojoCompositorFrameSink instances for use
+// with offscreen canvas.
+interface OffscreenCanvasProvider {
+  // TODO(kylechar): Observer interface shouldn't be DisplayCompositorClient.
+  // Create an OffscreenCanvasSurface for |frame_sink_id|. |client| will observe
+  // any changes to the SurfaceId associated with |frame_sink_id|.
   CreateOffscreenCanvasSurface(cc.mojom.FrameSinkId parent_frame_sink_id,
                                cc.mojom.FrameSinkId frame_sink_id,
                                cc.mojom.DisplayCompositorClient client,
-                               OffscreenCanvasSurface& service);
-};
+                               OffscreenCanvasSurface& surface);
 
-interface OffscreenCanvasCompositorFrameSinkProvider {
-  // TODO(fsamuel, xlai): Replace this with DisplayCompositor
+  // Create an MojoCompositorFrameSink for |frame_sink_id|. This must happen
+  // after creating an OffsreenCanvasSurface for |frame_sink_id|.
   CreateCompositorFrameSink(cc.mojom.FrameSinkId frame_sink_id,
                             cc.mojom.MojoCompositorFrameSinkClient client,
                             cc.mojom.MojoCompositorFrameSink& sink);
-};
-
+};