Update Panel UI looks on Windows.

chrome/browser/ui/panels/panel.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.
 
 #ifndef CHROME_BROWSER_UI_PANELS_PANEL_H_
 #define CHROME_BROWSER_UI_PANELS_PANEL_H_
 #pragma once
 
 #include "chrome/browser/ui/browser_window.h"
 
@@ skipping 24 matching lines @@
  public:
   enum ExpansionState {
    // The panel is fully expanded with both title-bar and the client-area.
    EXPANDED,
    // The panel is shown with the title-bar only.
    TITLE_ONLY,
    // The panel is shown with 3-pixel line.
    MINIMIZED
   };
 
-  // The panel can be minimized to 3-pixel lines.
-  static const int kMinimizedPanelHeight = 3;
+  // The panel can be minimized to 4-pixel lines.
+  static const int kMinimizedPanelHeight = 4;
 
   virtual ~Panel();
 
   // Returns the PanelManager associated with this panel.
   PanelManager* manager() const;
 
   // Gets the extension that a panel is created from.
   // Returns NULL if it cannot be found.
   const Extension* GetExtension() const;
 
@@ skipping 210 matching lines @@
   // Stores the full height of the panel so we can restore it after it's
   // been minimized.
   int restored_height_;
 
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(Panel);
 };
 
 #endif  // CHROME_BROWSER_UI_PANELS_PANEL_H_