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

chrome/browser/infobars/infobar_container.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_INFOBARS_INFOBAR_CONTAINER_H_
 #define CHROME_BROWSER_INFOBARS_INFOBAR_CONTAINER_H_
 
 #include <vector>
 
 #include "base/compiler_specific.h"
@@ skipping 92 matching lines @@
   // anything necessary to respond, e.g. re-layout.
   void OnInfoBarStateChanged(bool is_animating);
 
   // Called by |infobar| to request that it be removed from the container, as it
   // is about to delete itself.  At this point, |infobar| should already be
   // hidden.
   void RemoveInfoBar(InfoBar* infobar);
 
   const Delegate* delegate() const { return delegate_; }
 
   // InstantOverlayModelObserver:

[dhollowa, 2013/03/08 00:03:32]

This should be moved down under the SearchModelObserver: overrides.

[kuan, 2013/03/12 18:00:38]

this method has been removed.

   virtual void OverlayStateChanged(const InstantOverlayModel& model) OVERRIDE;
 
  protected:
   // Subclasses must call this during destruction, so that we can remove
   // infobars (which will call the pure virtual functions below) while the
   // subclass portion of |this| has not yet been destroyed.
   void RemoveAllInfoBarsForDestruction();
 
   // These must be implemented on each platform to e.g. adjust the visible
   // object hierarchy.
   virtual void PlatformSpecificAddInfoBar(InfoBar* infobar,
                                           size_t position) = 0;
   virtual void PlatformSpecificRemoveInfoBar(InfoBar* infobar) = 0;
   virtual void PlatformSpecificInfoBarStateChanged(bool is_animating) {}
 
  private:
   typedef std::vector<InfoBar*> InfoBars;
 
   // content::NotificationObserver:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   // chrome::search::SearchModelObserver:
   virtual void ModeChanged(const chrome::search::Mode& old_mode,
                            const chrome::search::Mode& new_mode) OVERRIDE;
+  virtual void TopBarsVisibilityChanged(const chrome::search::Mode& mode,
+                                        bool visible) OVERRIDE;
 
   // Hides an InfoBar for the specified delegate, in response to a notification
   // from the selected InfoBarService.  The InfoBar's disappearance will be
   // animated if |use_animation| is true and it has been more than 50ms since
   // infobars were reshown due to an Instant Extended mode change. The InfoBar
   // will call back to RemoveInfoBar() to remove itself once it's hidden (which
   // may mean synchronously).  Returns the position within |infobars_| the
   // infobar was previously at.
   size_t HideInfoBar(InfoBarDelegate* delegate, bool use_animation);
 
@@ skipping 30 matching lines @@
   // Extended.
   chrome::search::SearchModel* search_model_;
 
   // Calculated in SetMaxTopArrowHeight().
   int top_arrow_target_height_;
 
   DISALLOW_COPY_AND_ASSIGN(InfoBarContainer);
 };
 
 #endif  // CHROME_BROWSER_INFOBARS_INFOBAR_CONTAINER_H_