refactor EnumerateDevices to make it a persistent request.

webkit/plugins/ppapi/plugin_delegate.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 WEBKIT_PLUGINS_PPAPI_PLUGIN_DELEGATE_H_
 #define WEBKIT_PLUGINS_PPAPI_PLUGIN_DELEGATE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 641 matching lines @@
   typedef base::Callback<
       void (int /* request_id */,
             bool /* succeeded */,
             const std::vector< ::ppapi::DeviceRefData>& /* devices */)>
       EnumerateDevicesCallback;
 
   // Enumerates devices of the specified type. The request ID passed into the
   // callback will be the same as the return value.
   virtual int EnumerateDevices(PP_DeviceType_Dev type,
                                const EnumerateDevicesCallback& callback) = 0;
+  // Stop enumerating devices of the specified |request_id|. The |request_id|
+  // is the return value of EnumerateDevicesCallback.
+  virtual void StopEnumerateDevices(int request_id) = 0;
   // Create a ClipboardClient for writing to the clipboard. The caller will own
   // the pointer to this.
   virtual webkit_glue::ClipboardClient* CreateClipboardClient() const = 0;
 
   // Returns a Device ID
   virtual std::string GetDeviceID() = 0;
 
   // Returns restrictions on local data handled by the plug-in.
   virtual PP_FlashLSORestrictions GetLocalDataRestrictions(
       const GURL& document_url,
       const GURL& plugin_url) = 0;
 };
 
 }  // namespace ppapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_PPAPI_PLUGIN_DELEGATE_H_