Change the launcher to create new tabs instead of windows when

ash/launcher/launcher_delegate.h

 // 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.
 
 #ifndef ASH_LAUNCHER_LAUNCHER_DELEGATE_H_
 #define ASH_LAUNCHER_LAUNCHER_DELEGATE_H_
 #pragma once
 
 #include "ash/ash_export.h"
 #include "ash/launcher/launcher_types.h"
 #include "base/string16.h"
 
 namespace ui {
 class MenuModel;
 }
 
 namespace ash {
 
 // Delegate for the Launcher.
 class ASH_EXPORT LauncherDelegate {
  public:
   virtual ~LauncherDelegate() {}
 
   // Invoked when the user clicks on button in the launcher to create a new
-  // window.
-  virtual void CreateNewWindow() = 0;
+  // tab.
+  virtual void CreateNewTab() = 0;
 
   // Invoked when the user clicks on a window entry in the launcher.
   virtual void ItemClicked(const LauncherItem& item) = 0;
 
   // Returns the resource id of the image to show on the browser shortcut
   // button.
   virtual int GetBrowserShortcutResourceId() = 0;
 
   // Returns the title to display for the specified launcher item.
   virtual string16 GetTitle(const LauncherItem& item) = 0;
 
   // Returns the context menumodel for the specified item. Return NULL if there
   // should be no context menu. The caller takes ownership of the returned
   // model.
   virtual ui::MenuModel* CreateContextMenu(const LauncherItem& item) = 0;
 
   // Returns the id of the item associated with the specified window, or 0 if
   // there isn't one.
   virtual ash::LauncherID GetIDByWindow(aura::Window* window) = 0;
 };
 
 }  // namespace ash
 
 #endif  // ASH_LAUNCHER_LAUNCHER_DELEGATE_H_