RenderWidgetHost::WasHidden is called twice on each tab switch on Aura.

chrome/browser/ui/views/tab_contents/tab_contents_container.cc

 // Copyright (c) 2011 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 "chrome/browser/ui/views/tab_contents/tab_contents_container.h"
 
 #include <utility>
 
 #include "chrome/browser/ui/view_ids.h"
 #include "chrome/browser/ui/views/tab_contents/native_tab_contents_container.h"
@@ skipping 19 matching lines @@
 }
 
 TabContentsContainer::~TabContentsContainer() {
   if (web_contents_)
     RemoveObservers();
 }
 
 void TabContentsContainer::ChangeWebContents(WebContents* contents) {
   if (web_contents_) {
     native_container_->DetachContents(web_contents_);
-    web_contents_->WasHidden();
     RemoveObservers();
   }
   web_contents_ = contents;
   // When detaching the last tab of the browser ChangeWebContents is invoked
   // with NULL. Don't attempt to do anything in that case.
   if (web_contents_) {
     RenderWidgetHostViewChanged(web_contents_->GetRenderWidgetHostView());
     native_container_->AttachContents(web_contents_);
     AddObservers();
   }
@@ skipping 146 matching lines @@
   // us to clean up our state in case this happens.
   DCHECK(contents == web_contents_);
   ChangeWebContents(NULL);
 }
 
 void TabContentsContainer::RenderWidgetHostViewChanged(
     RenderWidgetHostView* new_view) {
   if (new_view)
     new_view->set_reserved_contents_rect(cached_reserved_rect_);
 }