Lazy load chrome.* APIs

chrome/renderer/resources/extensions/app_custom_bindings.js

Index: chrome/renderer/resources/extensions/app_custom_bindings.js
diff --git a/chrome/renderer/resources/extensions/app_custom_bindings.js b/chrome/renderer/resources/extensions/app_custom_bindings.js
index 1a8bbcc7d6dab3ecaf05cee5574a61aed13e9ca4..7fdfc262c2ffff1d8672ab23b45d2e36a1d291e1 100644
--- a/chrome/renderer/resources/extensions/app_custom_bindings.js
+++ b/chrome/renderer/resources/extensions/app_custom_bindings.js
@@ -2,9 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Custom bindings for the app API.
+// Custom binding for the app API.
 
 var appNatives = requireNative('app');
+var chrome = requireNative('chrome').GetChrome();
+var GetAvailability = requireNative('v8_context').GetAvailability;
+var DCHECK = requireNative('logging').DCHECK;
 
 // This becomes chrome.app
 var app = {
@@ -23,7 +26,7 @@ var app = {
 // documentation.
 app.__defineGetter__('isInstalled', appNatives.GetIsInstalled);
 
-// Called by app_bindings.cc.
+// Called by app_binding.cc.
 // This becomes chromeHidden.app
 var chromeHiddenApp = {
   onGetAppNotifyChannelResponse: function(channelId, error, callbackId) {
@@ -43,7 +46,7 @@ var chromeHiddenApp = {
 
 // appNotification stuff.
 //
-// TODO(kalman): move this stuff to its own custom bindings.
+// TODO(kalman): move this stuff to its own custom binding.
 // It will be bit tricky since I'll need to look into why there are
 // permissions defined for app notifications, yet this always sets it up?
 var callbacks = {};
@@ -67,8 +70,23 @@ app.installState = function getInstallState(callback) {
   appNatives.GetInstallState(callbackId);
 };
 
-// These must match the names in InstallAppBindings() in
+function defineCheckAvailabilityGetter(name, apiName, target) {

[not at google - send to devlin, 2013/02/13 01:45:49]

defineLazyGetter?

Comment why it's necessary?

[cduvall, 2013/02/15 00:40:28]

This actually doesn't need the lazy getter anymore.

+  exports.__defineGetter__(name, function() {
+    var availability = GetAvailability(apiName);
+    if (!availability.is_available) {
+      // If this API is not available, return undefined. An exception is not
+      // thrown like the other APIs because it is not guaranteed that this will
+      // be loaded in a try catch block.
+      return;

[not at google - send to devlin, 2013/02/13 01:45:49]

might as well say return undefined;

[cduvall, 2013/02/15 00:40:28]

Done.

+    }
+    return target;
+  });
+}
+
+// These must match the names in InstallAppbinding() in
 // chrome/renderer/extensions/dispatcher.cc.
-exports.chromeApp = app;
-exports.chromeAppNotifications = appNotifications;
-exports.chromeHiddenApp = chromeHiddenApp;
+defineCheckAvailabilityGetter('chromeApp', 'app', app);
+defineCheckAvailabilityGetter('chromeAppNotifications',
+                              'app',
+                               appNotifications);
+defineCheckAvailabilityGetter('chromeHiddenApp', 'app', chromeHiddenApp);