[Mac] Fixes janky animations in the omnibox popup....

chrome/browser/autocomplete/autocomplete_popup_view_mac.h

 // Copyright (c) 2010 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_AUTOCOMPLETE_AUTOCOMPLETE_POPUP_VIEW_MAC_H_
 #define CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_POPUP_VIEW_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include <string>
@@ skipping 88 matching lines @@
   static NSMutableAttributedString* ElideString(
       NSMutableAttributedString* aString,
       const std::wstring originalString,
       const gfx::Font& font,
       const float cellWidth);
 
  private:
   // Create the popup_ instance if needed.
   void CreatePopupIfNeeded();
 
+  // Sets the popup frame, animating to the new frame if the popup is shrinking,
+  // setting the frame immediately otherwise.  Does nothing if the popup is
+  // already animating to the given frame.
+  void SetPopupFrame(const NSRect frame);
+
   scoped_ptr<AutocompletePopupModel> model_;
   AutocompleteEditViewMac* edit_view_;
   NSTextField* field_;  // owned by tab controller
 
   // Child window containing a matrix which implements the popup.
   scoped_nsobject<NSWindow> popup_;
+  NSRect targetPopupFrame_;
 
   DISALLOW_COPY_AND_ASSIGN(AutocompletePopupViewMac);
 };
 
 #endif  // CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_POPUP_VIEW_MAC_H_