Implement lifetime observer on RenderWidgetHostViewBase.

content/browser/renderer_host/render_widget_host_view_aura.cc

 // 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.
 
 #include "content/browser/renderer_host/render_widget_host_view_aura.h"
 
 #include <set>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 2468 matching lines @@
   TRACE_EVENT1("ui", "RenderWidgetHostViewAura::OnHostMoved",
                "new_origin", new_origin.ToString());
 
   UpdateScreenInfo(window_);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewAura, private:
 
 RenderWidgetHostViewAura::~RenderWidgetHostViewAura() {
+  // If the observers were already notified through the Destroy() pathway, then
+  // this next call just returns.

[kenrb, 2016/02/22 17:05:10]

Is this comment necessary? RWHVA::Destroy() doesn't seem to notify observers.

[wjmaclean, 2016/02/23 13:13:26]

Done.

Ooops, slightly stale comment, removed. Actually, we may be able to remove this
call to NotifyObserversAboutShutdown() altogether, since we don't destroy
anything like a host_ here, and the RWHVB destructor will call this function
shortly.

+  NotifyObserversAboutShutdown();
+
   // Ask the RWH to drop reference to us.
   if (!is_guest_view_hack_)
     host_->ViewDestroyed();
 
   selection_controller_.reset();
   selection_controller_client_.reset();
 
-  if (host_->delegate() && host_->delegate()->GetInputEventRouter()) {
-    host_->delegate()->GetInputEventRouter()->RemoveSurfaceIdNamespaceOwner(
-        GetSurfaceIdNamespace());
-  }
   delegated_frame_host_.reset();
   window_observer_.reset();
   if (window_) {
     if (window_->GetHost())
       window_->GetHost()->RemoveObserver(this);
     UnlockMouse();
     aura::client::SetTooltipText(window_, NULL);
     gfx::Screen::GetScreen()->RemoveObserver(this);
 
     // This call is usually no-op since |this| object is already removed from
@@ skipping 555 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewBase, public:
 
 // static
 void RenderWidgetHostViewBase::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content