views: Extract Widget observer into its own header file.

chrome/browser/ui/views/location_bar/zoom_bubble_view.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 "chrome/browser/ui/views/location_bar/zoom_bubble_view.h"
 
 #include "base/bind.h"
 #include "base/message_loop.h"
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/views/layout/fill_layout.h"
+#include "ui/views/widget/widget.h"
 
 namespace {
 
 // The number of milliseconds the bubble should stay on the screen for if it
 // will automatically close.
 const int kBubbleCloseDelay = 400;
 
-}
+}  // namespace
 
 // static
 ZoomBubbleView* ZoomBubbleView::zoom_bubble_ = NULL;
 
 // static
 void ZoomBubbleView::ShowBubble(views::View* anchor_view,
                                 int zoom_percent,
                                 bool auto_close) {
   // If the bubble is already showing in this window and its |auto_close_| value
   // is equal to |auto_close|, the bubble can be reused and only the label text
@@ skipping 63 matching lines @@
         base::TimeDelta::FromMilliseconds(kBubbleCloseDelay),
         this,
         &ZoomBubbleView::Close);
   }
 }
 
 void ZoomBubbleView::WindowClosing() {
   DCHECK(zoom_bubble_ == this);
   zoom_bubble_ = NULL;
 }