Revamp OffscreenCanvas commit flow

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/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 {
-  // TODO(619138): Make creation of surface id Async after implementation
-  // change on surface_id generator that makes client side be able to generate
-  // unique surface_id.id_namespace alone.
-  [Sync]
-  GetSurfaceId() => (cc.mojom.SurfaceId surface_id);
+  SetClient(OffscreenCanvasSurfaceClient client,
+            cc.mojom.FrameSinkId frame_sink_id);
 
   Require(cc.mojom.SurfaceId surface_id, cc.mojom.SurfaceSequence sequence);
   Satisfy(cc.mojom.SurfaceSequence sequence);
 };
 
+interface OffscreenCanvasSurfaceClient {
+  OnSurfaceCreated(cc.mojom.SurfaceId surface_id,
+                   int32 width,
+                   int32 height,
+                   float device_scale_factor);
+};
+
 interface OffscreenCanvasCompositorFrameSinkProvider {
   CreateCompositorFrameSink(cc.mojom.SurfaceId surface_id,
                             cc.mojom.MojoCompositorFrameSinkClient client,
                             cc.mojom.MojoCompositorFrameSink& sink);
 };