Makes RenderFrameObserver/RenderViewObserver::OnDestruct pure virtual.

extensions/renderer/render_frame_observer_natives.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 "extensions/renderer/render_frame_observer_natives.h"
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "content/public/renderer/render_frame.h"
@@ skipping 21 matching lines @@
   }
 
   void DidFailProvisionalLoad(const blink::WebURLError& error) override {
     // Use PostTask to avoid running user scripts while handling this
     // DidFailProvisionalLoad notification.
     base::MessageLoop::current()->PostTask(FROM_HERE,
                                            base::Bind(callback_, false));
     delete this;
   }
 
+  void OnDestruct() override { delete this; }
+
  private:
   base::Callback<void(bool)> callback_;
 
   DISALLOW_COPY_AND_ASSIGN(LoadWatcher);
 };
 
 }  // namespace
 
 RenderFrameObserverNatives::RenderFrameObserverNatives(ScriptContext* context)
     : ObjectBackedNativeHandler(context), weak_ptr_factory_(this) {
@@ skipping 46 matching lines @@
     v8::Global<v8::Function> callback,
     bool succeeded) {
   v8::Isolate* isolate = context()->isolate();
   v8::HandleScope handle_scope(isolate);
   v8::Local<v8::Value> args[] = {v8::Boolean::New(isolate, succeeded)};
   context()->CallFunction(v8::Local<v8::Function>::New(isolate, callback),
                           arraysize(args), args);
 }
 
 }  // namespace extensions