Make app_custom_bindings.js lazily evaluated so it doesn't execute on every page load.

chrome/renderer/resources/extensions/webstore_custom_bindings.js

Index: chrome/renderer/resources/extensions/webstore_custom_bindings.js
diff --git a/chrome/renderer/resources/extensions/webstore_custom_bindings.js b/chrome/renderer/resources/extensions/webstore_custom_bindings.js
index 695b2a2d2743a8a0f3ff9f0041240e8528d43ea6..c2886b6c52b19adafa7acce894701a53803c23f1 100644
--- a/chrome/renderer/resources/extensions/webstore_custom_bindings.js
+++ b/chrome/renderer/resources/extensions/webstore_custom_bindings.js
@@ -4,7 +4,6 @@
 
 // Custom bindings for the webstore API.
 
-var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 var webstoreNatives = requireNative('webstore');
 
 function Installer() {
@@ -42,15 +41,18 @@ Installer.prototype.onInstallResponse = function(installId, success, error) {
 
 var installer = new Installer();
 
-chrome.webstore = {
+var chromeWebstore = {
   install: function install(url, onSuccess, onFailure) {
     installer.install(url, onSuccess, onFailure);
   }
 };
 
 // Called by webstore_bindings.cc.
-chromeHidden.webstore = {
+var chromeHiddenWebstore = {
   onInstallResponse: function(installId, success, error) {
     installer.onInstallResponse(installId, success, error);
   }
 };
+
+exports.chromeWebstore = chromeWebstore;
+exports.chromeHiddenWebstore = chromeHiddenWebstore;