Implement {Start,Stop}CapturingKeyStrokes for Instant.

chrome/renderer/resources/extensions/searchbox/searchbox_api.js

Index: chrome/renderer/resources/extensions/searchbox/searchbox_api.js
diff --git a/chrome/renderer/resources/extensions/searchbox/searchbox_api.js b/chrome/renderer/resources/extensions/searchbox/searchbox_api.js
index 23d4ce29c29b8865d4ef5e2c9436bec8b22c4c84..68cc65b5425cb0540ca239f07ee3b0a516751024 100644
--- a/chrome/renderer/resources/extensions/searchbox/searchbox_api.js
+++ b/chrome/renderer/resources/extensions/searchbox/searchbox_api.js
@@ -38,6 +38,8 @@ if (!chrome.searchBox) {
     native function SetQuery();
     native function SetQueryFromAutocompleteResult();
     native function Show();
+    native function WebSearchBoxGotFocus();
+    native function WebSearchBoxLostFocus();
 
     // Returns the |restrictedText| wrapped in a ShadowDOM.
     function SafeWrap(restrictedText) {
@@ -201,6 +203,12 @@ if (!chrome.searchBox) {
     this.navigateContentWindow = function(destination) {
       return NavigateContentWindow(destination);
     };
+    this.webSearchBoxGotFocus = function() {
+      WebSearchBoxGotFocus();
+    };
+    this.webSearchBoxLostFocus = function() {
+      WebSearchBoxLostFocus();
+    };
     this.onchange = null;
     this.onsubmit = null;
     this.oncancel = null;