Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

content/renderer/java/gin_java_bridge_dispatcher.cc

 // 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.
 
 #include "content/renderer/java/gin_java_bridge_dispatcher.h"
 
 #include "base/auto_reset.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/common/gin_java_bridge_messages.h"
@@ skipping 115 matching lines @@
 void GinJavaBridgeDispatcher::OnGinJavaBridgeObjectDeleted(
     GinJavaBridgeObject* object) {
   int object_id = object->object_id();
   // Ignore cleaning up of old object wrappers.
   if (objects_.Lookup(object_id) != object) return;
   objects_.Remove(object_id);
   render_frame()->Send(
       new GinJavaBridgeHostMsg_ObjectWrapperDeleted(routing_id(), object_id));
 }
 
+void GinJavaBridgeDispatcher::OnDestruct() {
+  delete this;
+}
+
 }  // namespace content