alternate ntp: toolbar background and separator animation

chrome/browser/ui/search/toolbar_search_animator_observer.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_SEARCH_TOOLBAR_SEARCH_ANIMATOR_OBSERVER_H_
 #define CHROME_BROWSER_UI_SEARCH_TOOLBAR_SEARCH_ANIMATOR_OBSERVER_H_
 
 class TabContents;
 
 namespace chrome {
 namespace search {
 
 // This class defines the observer interface for |ToolbarSearchAnimator|.
 class ToolbarSearchAnimatorObserver {
  public:
-  // Called from ui::AnimationDelegate::AnimationProgressed.
+  // Called from ui::AnimationDelegate::AnimationProgressed for fading in
+  // toolbar gradient background.
   virtual void OnToolbarBackgroundAnimatorProgressed() = 0;
 
-  // Called when animation is canceled and jumps to the end state.
+  // Called when toolbar gradient background animation is canceled and jumps to
+  // the end state.
   // If animation is canceled because the active tab is deactivated or detached
   // or closing, |tab_contents| contains the tab's contents.
   // Otherwise, if animation is canceled because of mode change, |tab_contents|
   // is NULL.
   virtual void OnToolbarBackgroundAnimatorCanceled(
       TabContents* tab_contents) = 0;
 
  protected:
   virtual ~ToolbarSearchAnimatorObserver() {}
 };
 
 }  // namespace search
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_UI_SEARCH_TOOLBAR_SEARCH_ANIMATOR_OBSERVER_H_