android: Fix ContentViewCore and RenderWidgetHostViewAndroid lifetime issue

content/public/browser/android/content_view_core.h

 // Copyright (c) 2012 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_PUBLIC_BROWSER_ANDROID_CONTENT_VIEW_CORE_H_
 #define CONTENT_PUBLIC_BROWSER_ANDROID_CONTENT_VIEW_CORE_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
@@ skipping 39 matching lines @@
   virtual void ShowPastePopup(int x, int y) = 0;
   virtual unsigned int GetScaledContentTexture(
       float scale,
       gfx::Size* out_size) = 0;
   virtual float GetDpiScale() const = 0;
   virtual void RequestContentClipping(const gfx::Rect& clipping,
                                       const gfx::Size& content_size) = 0;
   virtual void PauseVideo() = 0;
   virtual void ResumeVideo() = 0;
   virtual void PauseOrResumeGeolocation(bool should_pause) = 0;
+  virtual void OnDetachedFromWebContents(WebContents* web_contents) = 0;
 
   // Observer callback for frame metadata updates.
   typedef base::Callback<void(
       const gfx::SizeF& content_size,
       const gfx::Vector2dF& scroll_offset,
       float page_scale_factor)> UpdateFrameInfoCallback;
 
  protected:
   virtual ~ContentViewCore() {};
 };
 
 };  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_ANDROID_CONTENT_VIEW_CORE_H_