Implement {Start,Stop}CapturingKeyStrokes for Instant.

chrome/renderer/resources/extensions/searchbox_api.js

Index: chrome/renderer/resources/extensions/searchbox_api.js
diff --git a/chrome/renderer/resources/extensions/searchbox_api.js b/chrome/renderer/resources/extensions/searchbox_api.js
index fd6cd6200839b9f3a5c51b842b5a423a48b0b249..43eadbb6dd6c95d767608475c6a410d5555015dc 100644
--- a/chrome/renderer/resources/extensions/searchbox_api.js
+++ b/chrome/renderer/resources/extensions/searchbox_api.js
@@ -37,6 +37,7 @@ if (!chrome.searchBox) {
     native function SetQuery();
     native function SetQueryFromAutocompleteResult();
     native function Show();
+    native function WebSearchBoxFocusChange();
 
     // Returns the |restrictedText| wrapped in a ShadowDOM.
     function SafeWrap(restrictedText) {
@@ -199,6 +200,12 @@ if (!chrome.searchBox) {
     this.navigateContentWindow = function(destination) {
       return NavigateContentWindow(destination);
     };
+    this.webSearchBoxGotFocus = function() {
+      WebSearchBoxFocusChange(true);
+    };
+    this.webSearchBoxLostFocus = function() {
+      WebSearchBoxFocusChange(false);
+    };
     this.onchange = null;
     this.onsubmit = null;
     this.oncancel = null;