Refactor the way singleton-style resources are exposed via PPB_Instance

ppapi/proxy/plugin_dispatcher.h

 // 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.
 
 #ifndef PPAPI_PROXY_PLUGIN_DISPATCHER_H_
 #define PPAPI_PROXY_PLUGIN_DISPATCHER_H_
 
 #include <set>
 #include <string>
 
@@ skipping 33 matching lines @@
   InstanceData();
   ~InstanceData();
 
   ViewData view;
 
   PP_Bool flash_fullscreen;  // Used for PPB_FlashFullscreen.
 
   // When non-NULL, indicates the callback to execute when mouse lock is lost.
   scoped_refptr<TrackedCallback> mouse_lock_callback;
 
-  // The following are lazily created the first time the plugin requests them.
-  // (These are singleton-style resources).
-  scoped_refptr<GamepadResource> gamepad_resource;
-  scoped_refptr<FlashResource> flash_resource;
-  scoped_refptr<FlashClipboardResource> flash_clipboard_resource;
+  // A map of singleton resources which are lazily created.
+  typedef std::map<SingletonResourceID, scoped_refptr<Resource> >
+      SingletonResourceMap;
+  SingletonResourceMap singleton_resources;
 
   // Calls to |RequestSurroundingText()| are done by posted tasks. Track whether
   // a) a task is pending, to avoid redundant calls, and b) whether we should
   // actually call |RequestSurroundingText()|, to avoid stale calls (i.e.,
   // calling when we shouldn't).
   bool is_request_surrounding_text_pending;
   bool should_do_request_surrounding_text;
 };
 
 class PPAPI_PROXY_EXPORT PluginDispatcher
@@ skipping 142 matching lines @@
   // incognito mode.
   bool incognito_;
 
   DISALLOW_COPY_AND_ASSIGN(PluginDispatcher);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_PLUGIN_DISPATCHER_H_