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

chrome/renderer/resources/extensions/searchbox_api.js

 // Copyright 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.
 
 var chrome;
 if (!chrome)
   chrome = {};
 
 if (!chrome.embeddedSearch) {
   chrome.embeddedSearch = new function() {
@@ skipping 87 matching lines @@
       native function SetQuery();
       native function SetQueryFromAutocompleteResult();
       native function SetSuggestion();
       native function SetSuggestionFromAutocompleteResult();
       native function SetSuggestions();
       native function ShowOverlay();
       native function FocusOmnibox();
       native function StartCapturingKeyStrokes();
       native function StopCapturingKeyStrokes();
       native function NavigateSearchBox();
+      native function ShowBars();
+      native function HideBars();
 
       function SafeWrapSuggestion(restrictedText) {
         return SafeWrap(restrictedText, window.innerWidth - 155, 22);
       }
 
       // Wraps the AutocompleteResult query and URL into ShadowDOM nodes so that
       // the JS cannot access them and deletes the raw values.
       function GetAutocompleteResultsWrapper() {
         var autocompleteResults = DedupeAutocompleteResults(
             GetAutocompleteResults());
@@ skipping 145 matching lines @@
       };
       this.startCapturingKeyStrokes = function() {
         StartCapturingKeyStrokes();
       };
       this.stopCapturingKeyStrokes = function() {
         StopCapturingKeyStrokes();
       };
       this.navigateContentWindow = function(destination, disposition) {
         NavigateSearchBox(destination, disposition);
       }
+      this.showBars = function() {
+        ShowBars();
+      };
+      this.hideBars = function() {
+        HideBars();
+      };
       this.onchange = null;
       this.onsubmit = null;
       this.oncancel = null;
       this.onresize = null;
       this.onkeypress = null;
       this.onkeycapturechange = null;
       this.onmarginchange = null;
       this.onnativesuggestions = null;
+      this.onbarshidden = null;
 
       // DEPRECATED. These methods are from the legacy searchbox API.
       // TODO(jered): Delete these.
       native function GetX();
       native function GetY();
       native function GetWidth();
       native function GetHeight();
       this.__defineGetter__('x', GetX);
       this.__defineGetter__('y', GetY);
       this.__defineGetter__('width', GetWidth);
@@ skipping 51 matching lines @@
 
       this.onmostvisitedchange = null;
       this.onthemechange = null;
     };
 
     // Export legacy searchbox API.
     // TODO: Remove this when Instant Extended is fully launched.
     chrome.searchBox = this.searchBox;
   };
 }