Replace context parenting by sharing through mailboxes

ppapi/proxy/ppapi_command_buffer_proxy.cc

 // Copyright (c) 2012 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.
 
 #include "ppapi/proxy/ppapi_command_buffer_proxy.h"
 
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/proxy_channel.h"
 #include "ppapi/shared_impl/api_id.h"
 #include "ppapi/shared_impl/host_resource.h"
@@ skipping 27 matching lines @@
 
 int PpapiCommandBufferProxy::GetRouteID() const {
   NOTIMPLEMENTED();
   return 0;
 }
 
 bool PpapiCommandBufferProxy::Echo(const base::Closure& callback) {
   return false;
 }
 
-bool PpapiCommandBufferProxy::SetParent(
-    CommandBufferProxy* parent_command_buffer,
-    uint32 parent_texture_id) {
-  // TODO(fsamuel): Need a proper implementation of this to support offscreen
-  // contexts in the guest renderer (WebGL, canvas, etc).
+bool PpapiCommandBufferProxy::ProduceFrontBuffer(const gpu::Mailbox& mailbox) {
   NOTIMPLEMENTED();
   return false;
 }
 
 void PpapiCommandBufferProxy::SetChannelErrorCallback(
     const base::Closure& callback) {
   channel_error_callback_ = callback;
 }
 
 bool PpapiCommandBufferProxy::Initialize() {
@@ skipping 191 matching lines @@
       last_state_ = state;
     }
   } else {
     last_state_.error = gpu::error::kLostContext;
     ++last_state_.generation;
   }
 }
 
 }  // namespace proxy
 }  // namespace ppapi