Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

content/renderer/media/cdm/renderer_cdm_manager.h

 // Copyright 2014 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_CDM_RENDERER_CDM_MANAGER_H_
 #define CONTENT_RENDERER_MEDIA_CDM_RENDERER_CDM_MANAGER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 56 matching lines @@
                      const std::string& session_id);
   void DestroyCdm(int cdm_id);
 
   // Registers a ProxyMediaKeys object. Returns allocated CDM ID.
   int RegisterMediaKeys(ProxyMediaKeys* media_keys);
 
   // Unregisters a ProxyMediaKeys object identified by |cdm_id|.
   void UnregisterMediaKeys(int cdm_id);
 
  private:
+  // RenderFrameObserver implementation.
+  void OnDestruct() override;
+
   // Gets the pointer to ProxyMediaKeys given the |cdm_id|.
   ProxyMediaKeys* GetMediaKeys(int cdm_id);
 
   // Message handlers.
   void OnSessionMessage(int cdm_id,
                         const std::string& session_id,
                         media::MediaKeys::MessageType message_type,
                         const std::vector<uint8_t>& message,
                         const GURL& legacy_destination_url);
   void OnSessionClosed(int cdm_id, const std::string& session_id);
@@ skipping 27 matching lines @@
 
   // CDM ID to ProxyMediaKeys mapping.
   std::map<int, ProxyMediaKeys*> proxy_media_keys_map_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererCdmManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_CDM_RENDERER_CDM_MANAGER_H_