Convert Google Now's Authentication Manager to use Promises

chrome/browser/resources/google_now/utility.js

Index: chrome/browser/resources/google_now/utility.js
diff --git a/chrome/browser/resources/google_now/utility.js b/chrome/browser/resources/google_now/utility.js
index aa20066306585f1ed6b2194fd1716085e9f063eb..aada2e59f5cdb182b8c7b4adcca2462392a28be7 100644
--- a/chrome/browser/resources/google_now/utility.js
+++ b/chrome/browser/resources/google_now/utility.js
@@ -726,36 +726,45 @@ function buildAuthenticationManager() {
 
   /**
    * Gets an OAuth2 access token.
-   * @param {function(string=)} callback Called on completion.
-   *     The string contains the token. It's undefined if there was an error.
+   * @return {Promise} A promise to get the authentication token. If there is
+   *     no token, the request is rejected.
    */
-  function getAuthToken(callback) {
-    instrumented.identity.getAuthToken({interactive: false}, function(token) {
-      token = chrome.runtime.lastError ? undefined : token;
-      callback(token);
+  function getAuthToken() {
+    return new Promise(function(resolve, reject) {
+      instrumented.identity.getAuthToken({interactive: false}, function(token) {
+        if (chrome.runtime.lastError || !token) {
+          reject();
+        } else {
+          resolve(token);
+        }
+      });
     });
   }
 
   /**
    * Determines whether there is an account attached to the profile.
-   * @param {function(boolean)} callback Called on completion.
+   * @return {Promise} A promise to determine if there is an account attached
+   *     to the profile.
    */
-  function isSignedIn(callback) {
-    instrumented.webstorePrivate.getBrowserLogin(function(accountInfo) {
-      callback(!!accountInfo.login);
+  function isSignedIn() {
+    return new Promise(function(resolve) {
+      instrumented.webstorePrivate.getBrowserLogin(function(accountInfo) {
+        resolve(!!accountInfo.login);
+      });
     });
   }
 
   /**
    * Removes the specified cached token.
    * @param {string} token Authentication Token to remove from the cache.
-   * @param {function()} callback Called on completion.
+   * @return {Promise} A promise that resolves on completion.
    */
-  function removeToken(token, callback) {
-    instrumented.identity.removeCachedAuthToken({token: token}, function() {
-      // Let Chrome now about a possible problem with the token.

[rgustafson, 2014/02/13 21:31:40]

Keep the comment in, but now -> know. It's not immediately obvious why there's a
get call after removing it.

[robliao, 2014/02/13 21:41:33]

Done.

-      getAuthToken(function() {});
-      callback();
+  function removeToken(token) {
+    return new Promise(function(resolve) {
+      instrumented.identity.removeCachedAuthToken({token: token}, function() {
+        getAuthToken();
+        resolve();
+      });
     });
   }