Send size to NativeViewportClient::OnCreated instead of GLES2Client::DidCreateContext

mojo/services/gles2/gles2.mojom

 // Copyright 2013 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 mojo {
 
 [Peer=GLES2Client]
 interface GLES2 {
   void RequestAnimationFrames();
   void CancelAnimationFrames();
   void Destroy();
 };
 
 [Peer=GLES2]
 interface GLES2Client {
-  void DidCreateContext(uint64 encoded, uint32 width, uint32 height);
+  void DidCreateContext(uint64 encoded);
   void ContextLost();
   void DrawAnimationFrame();
 };
 
 }