Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

content/renderer/mojo_bindings_controller.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_MOJO_BINDINGS_CONTROLLER_H_
 #define CONTENT_RENDERER_MOJO_BINDINGS_CONTROLLER_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 25 matching lines @@
   ~MojoBindingsController() override;
 
   void CreateContextState();
   void DestroyContextState(v8::Local<v8::Context> context);
   MojoContextState* GetContextState();
 
   // RenderFrameObserver overrides:
   void WillReleaseScriptContext(v8::Local<v8::Context> context,
                                 int world_id) override;
   void DidClearWindowObject() override;
+  void OnDestruct() override;
 
   const bool for_layout_tests_;
 
   DISALLOW_COPY_AND_ASSIGN(MojoBindingsController);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MOJO_BINDINGS_CONTROLLER_H_