Add a virtual destructor to PermissionPromptDelegate

chrome/browser/media/webrtc/media_stream_devices_controller.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 CHROME_BROWSER_MEDIA_WEBRTC_MEDIA_STREAM_DEVICES_CONTROLLER_H_
 #define CHROME_BROWSER_MEDIA_WEBRTC_MEDIA_STREAM_DEVICES_CONTROLLER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 73 matching lines @@
   // This class is only needed interally and for tests. It can be removed once
   // crbug.com/606138 is fixed. Delegate for showing permission prompts. It's
   // only public because subclassing from a friend class doesn't work in gcc
   // (see https://codereview.chromium.org/2768923003).
   class PermissionPromptDelegate {
    public:
     virtual void ShowPrompt(
         bool user_gesture,
         content::WebContents* web_contents,
         std::unique_ptr<MediaStreamDevicesController::Request> request) = 0;
+    virtual ~PermissionPromptDelegate() {}
   };
 
   static void RequestPermissions(
       const content::MediaStreamRequest& request,
       const content::MediaResponseCallback& callback);
 
   // Registers the prefs backing the audio and video policies.
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
   ~MediaStreamDevicesController();
@@ skipping 79 matching lines @@
   // The callback that needs to be Run to notify WebRTC of whether access to
   // audio/video devices was granted or not.
   content::MediaResponseCallback callback_;
 
   std::unique_ptr<PermissionPromptDelegate> delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaStreamDevicesController);
 };
 
 #endif  // CHROME_BROWSER_MEDIA_WEBRTC_MEDIA_STREAM_DEVICES_CONTROLLER_H_