Cleanup: Remove unneeded forward declarations from various chrome/browser subdirectories.

chrome/browser/notifications/balloon.h

 // 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.
 
 // Handles the visible notification (or balloons).
 
 #ifndef CHROME_BROWSER_NOTIFICATIONS_BALLOON_H_
 #define CHROME_BROWSER_NOTIFICATIONS_BALLOON_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 
 class Balloon;
 class BalloonCollection;
 class BalloonHost;
 class Notification;
 class Profile;
-class SiteInstance;
 
 // Interface for a view that displays a balloon.
 class BalloonView {
  public:
   virtual ~BalloonView() { }
 
   // Show the view on the screen.
   virtual void Show(Balloon* balloon) = 0;
 
   // Notify that the content of notification has chagned.
@@ skipping 96 matching lines @@
   // position for keeping the close buttons under the mouse cursor.
   gfx::Point offset_;
 
   // Smallest size for this balloon where scrollbars will be shown.
   gfx::Size min_scrollbar_size_;
 
   DISALLOW_COPY_AND_ASSIGN(Balloon);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_BALLOON_H_