Re-check existence of GuestViewContainer before requesting attach.

components/guest_view/renderer/guest_view_container.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 COMPONENTS_GUEST_VIEW_RENDERER_GUEST_VIEW_CONTAINER_H_
 #define COMPONENTS_GUEST_VIEW_RENDERER_GUEST_VIEW_CONTAINER_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 48 matching lines @@
   virtual void OnReady() {}
 
   // Called to perform actions when a GuestViewContainer is about to be
   // destroyed.
   // Note that this should be called exactly once.
   virtual void OnDestroy(bool embedder_frame_destroyed) {}
 
   // BrowserPluginGuestDelegate public implementation.
   void SetElementInstanceID(int element_instance_id) final;
   void DidResizeElement(const gfx::Size& new_size) override;
+  base::WeakPtr<BrowserPluginDelegate> GetWeakPtr() final;
 
  protected:
   ~GuestViewContainer() override;
 
   bool ready_;
 
   void OnHandleCallback(const IPC::Message& message);
 
  private:
   class RenderFrameLifetimeObserver;
   friend class RenderFrameLifetimeObserver;
 
   void RenderFrameDestroyed();
 
   void EnqueueRequest(std::unique_ptr<GuestViewRequest> request);
   void PerformPendingRequest();
   void HandlePendingResponseCallback(const IPC::Message& message);
   void RunDestructionCallback(bool embedder_frame_destroyed);
   void CallElementResizeCallback(const gfx::Size& new_size);
 
   // BrowserPluginDelegate implementation.
   void Ready() final;
   void DidDestroyElement() final;
-  base::WeakPtr<BrowserPluginDelegate> GetWeakPtr() final;
 
   int element_instance_id_;
   content::RenderFrame* render_frame_;
   std::unique_ptr<RenderFrameLifetimeObserver> render_frame_lifetime_observer_;
 
   bool in_destruction_;
 
   std::deque<std::unique_ptr<GuestViewRequest>> pending_requests_;
   std::unique_ptr<GuestViewRequest> pending_response_;
 
   v8::Global<v8::Function> destruction_callback_;
   v8::Isolate* destruction_isolate_;
 
   v8::Global<v8::Function> element_resize_callback_;
   v8::Isolate* element_resize_isolate_;
 
   base::WeakPtrFactory<GuestViewContainer> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GuestViewContainer);
 };
 
 }  // namespace guest_view
 
 #endif  // COMPONENTS_GUEST_VIEW_RENDERER_GUEST_VIEW_CONTAINER_H_