Mojo JS: Attempt to simplify bindTo* related code.

chrome/test/data/webui/plugins_browsertest.js

Index: chrome/test/data/webui/plugins_browsertest.js
diff --git a/chrome/test/data/webui/plugins_browsertest.js b/chrome/test/data/webui/plugins_browsertest.js
index 76d57bd4edf343575e56729c74128a0a8a0ad695..e1a7569f529f20aed6654dc7b62c707eeeab3422 100644
--- a/chrome/test/data/webui/plugins_browsertest.js
+++ b/chrome/test/data/webui/plugins_browsertest.js
@@ -58,8 +58,6 @@ PluginsTest.prototype = {
        * @private
        */
       this.pluginsData_ = [];
-
-      this.pageProxy = null;
     };
 
     TestBrowserProxy.prototype = {
@@ -167,7 +165,7 @@ TEST_F('PluginsTest', 'Plugins', function() {
       var plugins = document.querySelectorAll('.plugin');
       assertEquals(EXPECTED_PLUGINS, plugins.length);
 
-      pageProxy.onPluginsUpdated([fakePluginData]);
+      pageImpl.onPluginsUpdated([fakePluginData]);
       plugins = document.querySelectorAll('.plugin');
       assertEquals(1, plugins.length);
     });