Implement a module system for the extension bindings JS.

chrome/renderer/resources/extensions/extension_custom_bindings.js

Index: chrome/renderer/resources/extensions/extension_custom_bindings.js
diff --git a/chrome/renderer/resources/extensions/extension_custom_bindings.js b/chrome/renderer/resources/extensions/extension_custom_bindings.js
index f746e2a4761a7f345cc30134435bcfc2f3e5952c..970e11f9ad24286b379e657737277aee15118618 100644
--- a/chrome/renderer/resources/extensions/extension_custom_bindings.js
+++ b/chrome/renderer/resources/extensions/extension_custom_bindings.js
@@ -4,13 +4,11 @@
 
 // Custom bindings for the extension API.
 
-(function() {
+var extensionNatives = requireNative('extension');
+var GetExtensionViews = extensionNatives.GetExtensionViews;
+var OpenChannelToExtension = extensionNatives.OpenChannelToExtension;
 
-native function GetChromeHidden();
-native function GetExtensionViews();
-native function OpenChannelToExtension(sourceId, targetId, name);
-
-var chromeHidden = GetChromeHidden();
+var chromeHidden = requireNative('chrome_hidden').GetChromeHidden();
 
 // This should match chrome.windows.WINDOW_ID_NONE.
 //
@@ -144,5 +142,3 @@ chromeHidden.registerCustomHook('extension',
     throw new Error('Error connecting to extension ' + targetId);
   });
 });
-
-})();