Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

content/renderer/media/user_media_client_impl.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 CONTENT_RENDERER_MEDIA_USER_MEDIA_CLIENT_IMPL_H_
 #define CONTENT_RENDERER_MEDIA_USER_MEDIA_CLIENT_IMPL_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 178 matching lines @@
   UserMediaRequestInfo* FindUserMediaRequestInfo(
       const blink::WebUserMediaRequest& request);
 
   void DeleteUserMediaRequestInfo(UserMediaRequestInfo* request);
 
  private:
   typedef std::vector<blink::WebMediaStreamSource> LocalStreamSources;
   struct MediaDevicesRequestInfo;
   typedef ScopedVector<MediaDevicesRequestInfo> MediaDevicesRequests;
 
+  // RenderFrameObserver implementation.
+  void OnDestruct() override;
+
   // Creates a WebKit representation of stream sources based on
   // |devices| from the MediaStreamDispatcher.
   void InitializeSourceObject(
       const StreamDeviceInfo& device,
       blink::WebMediaStreamSource::Type type,
       const blink::WebMediaConstraints& constraints,
       blink::WebMediaStreamSource* webkit_source);
 
   void CreateVideoTracks(
       const StreamDeviceInfoArray& devices,
@@ skipping 62 matching lines @@
   // Note: This member must be the last to ensure all outstanding weak pointers
   // are invalidated first.
   base::WeakPtrFactory<UserMediaClientImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(UserMediaClientImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_USER_MEDIA_CLIENT_IMPL_H_