MD Settings: create a shared handler/browser proxy to control extensions

chrome/test/data/webui/settings/search_engines_page_test.js

Index: chrome/test/data/webui/settings/search_engines_page_test.js
diff --git a/chrome/test/data/webui/settings/search_engines_page_test.js b/chrome/test/data/webui/settings/search_engines_page_test.js
index b36502a3e20ca4cb09daf9943271de35a65a6df9..ec389e0d7faf4efbce39a64a2f656b5ea70a8576 100644
--- a/chrome/test/data/webui/settings/search_engines_page_test.js
+++ b/chrome/test/data/webui/settings/search_engines_page_test.js
@@ -341,8 +341,8 @@ cr.define('settings_search_engines_page', function() {
       var browserProxy = null;
 
       setup(function() {
-        browserProxy = new settings_search.TestSearchEnginesBrowserProxy();
-        settings.SearchEnginesBrowserProxyImpl.instance_ = browserProxy;
+        browserProxy = new TestExtensionControlBrowserProxy();
+        settings.ExtensionControlBrowserProxyImpl.instance_ = browserProxy;
         PolymerTest.clearBody();
         entry = document.createElement('settings-omnibox-extension-entry');
         entry.set('engine', createSampleOmniboxExtension());