Implement lifetime observer on RenderWidgetHostViewBase.

content/browser/renderer_host/render_widget_host_view_aura.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_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 335 matching lines @@
 
  protected:
   ~RenderWidgetHostViewAura() override;
 
   // Exposed for tests.
   aura::Window* window() { return window_; }
 
   DelegatedFrameHost* GetDelegatedFrameHost() const {
     return delegated_frame_host_.get();
   }
+
   const ui::MotionEventAura& pointer_state() const { return pointer_state_; }
 
  private:
   friend class RenderWidgetHostViewAuraCopyRequestTest;
   FRIEND_TEST_ALL_PREFIXES(RenderWidgetHostViewAuraTest,
                            PopupRetainsCaptureAfterMouseRelease);
   FRIEND_TEST_ALL_PREFIXES(RenderWidgetHostViewAuraTest, SetCompositionText);
   FRIEND_TEST_ALL_PREFIXES(RenderWidgetHostViewAuraTest, TouchEventState);
   FRIEND_TEST_ALL_PREFIXES(RenderWidgetHostViewAuraTest,
                            TouchEventPositionsArentRounded);
@@ skipping 331 matching lines @@
   float device_scale_factor_;
 
   base::WeakPtrFactory<RenderWidgetHostViewAura> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewAura);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_AURA_H_