Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

content/renderer/java/gin_java_bridge_dispatcher.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_JAVA_GIN_JAVA_BRIDGE_DISPATCHER_H_
 #define CONTENT_RENDERER_JAVA_GIN_JAVA_BRIDGE_DISPATCHER_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 41 matching lines @@
   bool HasJavaMethod(ObjectID object_id, const std::string& method_name);
   std::unique_ptr<base::Value> InvokeJavaMethod(
       ObjectID object_id,
       const std::string& method_name,
       const base::ListValue& arguments,
       GinJavaBridgeError* error);
   GinJavaBridgeObject* GetObject(ObjectID object_id);
   void OnGinJavaBridgeObjectDeleted(GinJavaBridgeObject* object);
 
  private:
+  // RenderFrameObserver implementation.
+  void OnDestruct() override;
+
   void OnAddNamedObject(const std::string& name,
                         ObjectID object_id);
   void OnRemoveNamedObject(const std::string& name);
   void OnSetAllowObjectContentsInspection(bool allow);
 
   typedef std::map<std::string, ObjectID> NamedObjectMap;
   NamedObjectMap named_objects_;
   ObjectMap objects_;
   bool inside_did_clear_window_object_;
 
   DISALLOW_COPY_AND_ASSIGN(GinJavaBridgeDispatcher);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_JAVA_GIN_JAVA_BRIDGE_DISPATCHER_H_