Add a unified resource tracker shared between the proxy and the impl.

ppapi/proxy/plugin_resource.cc

-// Copyright (c) 2011 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/plugin_resource.h"
-
-using ppapi::HostResource;
-
-namespace pp {
-namespace proxy {
-
-PluginResource::PluginResource(const HostResource& resource)
-    : ResourceObjectBase(resource.instance()),
-      host_resource_(resource) {
-}
-
-PluginResource::~PluginResource() {
-}
-
-PluginDispatcher* PluginResource::GetDispatcher() {
-  PluginDispatcher* disp = PluginDispatcher::GetForInstance(instance());
-  CHECK(disp);
-  return disp;
-}
-
-}  // namespace proxy
-}  // namespace pp