alternate ntp: implement Show/HideBars API to reduce jank when showing/hiding bars

chrome/browser/ui/cocoa/browser_window_cocoa.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 CHROME_BROWSER_UI_COCOA_BROWSER_WINDOW_COCOA_H_
 #define CHROME_BROWSER_UI_COCOA_BROWSER_WINDOW_COCOA_H_
 
 #include "base/memory/scoped_nsobject.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/bookmarks/bookmark_model.h"
@@ skipping 131 matching lines @@
   virtual void ShowPasswordGenerationBubble(
       const gfx::Rect& rect,
       const content::PasswordForm& form,
       autofill::PasswordGenerator* password_generator) OVERRIDE;
 
   // Overridden from ExtensionKeybindingRegistry::Delegate:
   virtual extensions::ActiveTabPermissionGranter*
       GetActiveTabPermissionGranter() OVERRIDE;
 
   // Overridden from chrome::search::SearchModelObserver:
-  virtual void ModeChanged(const chrome::search::Mode& old_mode,
-                           const chrome::search::Mode& new_mode) OVERRIDE;
+  virtual void ModelChanged(
+      const chrome::search::SearchModel::State& old_state,
+      const chrome::search::SearchModel::State& new_state) OVERRIDE;
 
   // Adds the given FindBar cocoa controller to this browser window.
   void AddFindBar(FindBarCocoaController* find_bar_cocoa_controller);
 
   // Returns the cocoa-world BrowserWindowController
   BrowserWindowController* cocoa_controller() { return controller_; }
 
  protected:
   virtual void DestroyBrowser() OVERRIDE;
 
  private:
   NSWindow* window() const;  // Accessor for the (current) |NSWindow|.
 
   Browser* browser_;  // weak, owned by controller
   BrowserWindowController* controller_;  // weak, owns us
   base::WeakPtrFactory<Browser> confirm_close_factory_;
   scoped_nsobject<NSString> pending_window_title_;
   ui::WindowShowState initial_show_state_;
   NSInteger attention_request_id_;  // identifier from requestUserAttention
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_BROWSER_WINDOW_COCOA_H_