Convert now component to use GCM rather than pushMessaging.

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 dfcb8d8f3ad66b7c2d4534f4866932266826c1bc..b28cf5385f7012ecc2a2075b1f02385cfbaf8d77 100644
--- a/chrome/browser/resources/google_now/utility.js
+++ b/chrome/browser/resources/google_now/utility.js
@@ -30,6 +30,17 @@
 var NOTIFICATION_CARDS_URL = 'https://www.googleapis.com/chromenow/v1';
 
 /**
+ * GCM registration URL.
+ */
+var GCM_REGISTRATION_URL =
+    'https://android.googleapis.com/gcm/googlenotification';
+
+/**
+ * DevConsole project ID for GCM API use.
+ */
+var GCM_PROJECT_ID = '437902709571';
+
+/**
  * Returns true if debug mode is enabled.
  * localStorage returns items as strings, which means if we store a boolean,
  * it returns a string. Use this function to compare against true.
@@ -1059,3 +1070,116 @@ function buildAuthenticationManager() {
     removeToken: removeToken
   };
 }
+
+/**
+ * Ensures the extension is ready to listen for GCM messages.
+ */
+function registerForGcm() {
+  // We don't need to use the key at this point, just ensure it's set up,
+  getGcmNotificationKey().then(function(unusedKey) {});
+}
+
+/**
+ * Returns a Promise resolving to either a cached or new GCM notification key.
+ * Rejects if registration fails.
+ * @return {Promise} A Promise that resolves to a potentially-cached GCM key.
+ */
+function getGcmNotificationKey() {
+  return fillFromChromeLocalStorage({gcmNotificationKey: undefined})
+      .then(function(items) {
+        return new Promise(function(resolve, reject) {
+          if (items.gcmNotificationKey) {
+            console.log('reused gcm key from storage.');
+            resolve(items.gcmNotificationKey);
+          } else {
+            requestNewGcmNotificationKey().then(function(key) {
+              resolve(key);
+            }).catch(function() {
+              reject();

[robliao, 2015/02/18 00:04:25]

I think this can be written as...

fillFromChromeLocalStorage({gcmNotificationKey: undefined})
    .then(function(items) {
      if (items.gcmNotificationKey) {
        console.log('Reused GCM Key from Storage');
        return Promise.resolve(items.gcmNotificationKey);
      }

      return requestNewGcmNotificationKey();
    }

[skare_, 2015/02/19 16:48:10]

yes it can. thanks, done.

+            });
+          }
+        });
+      });
+}
+
+/**
+ * Determines the active account's username.
+ * @return {Promise} A promise to determine the current account's username.
+ */
+function getUsername() {

[robliao, 2015/02/18 00:04:25]

Would it make sense to have the authentication manager handle this and return
the login?

[skare_, 2015/02/19 16:48:10]

Done.

+  return new Promise(function(resolve) {
+    instrumented.webstorePrivate.getBrowserLogin(function(accountInfo) {
+      resolve(accountInfo.login);
+    });
+  });
+}
+
+/**
+ * Returns a promise resolving to a GCM Notificaiton Key. May call
+ * chrome.gcm.register() first if required. Rejects on registration failure.
+ * @return {Promise} A Promise that resolves to a fresh GCM Notification key.
+ */
+function requestNewGcmNotificationKey() {
+  return getGcmRegistrationId().then(function(gcmId) {
+    authenticationManager.getAuthToken().then(function(token) {
+      getUsername().then(function(username) {
+        return new Promise(function(resolve, reject) {
+          var xhr = new XMLHttpRequest();
+          xhr.responseType = 'text';
+          xhr.open('POST', GCM_REGISTRATION_URL, true);
+          xhr.setRequestHeader('Content-Type', 'application/json');
+          xhr.setRequestHeader('Authorization', 'Bearer ' + token);
+          xhr.setRequestHeader('project_id', GCM_PROJECT_ID);
+          var payload = {
+            'operation': 'add',
+            'notification_key_name': username,
+            'registration_ids': [gcmId]
+          };
+          xhr.onloadend = function() {
+            if (xhr.status != 200) {
+              reject();
+            }
+            var obj = JSON.parse(xhr.responseText);
+            var key = obj && obj.notification_key;
+            if (!key) {
+              reject();
+            }
+            console.log('gcm notification key POST: ' + key);
+            chrome.storage.local.set({gcmNotificationKey: key});
+            resolve(key);
+          };
+          xhr.send(JSON.stringify(payload));
+        });
+      });
+    }).catch(function() {
+      // Couldn't obtain a GCM ID. Ignore and fallback to polling.
+    });
+  });
+}
+
+/**
+ * Returns a promise resolving to either a cached or new GCM registration ID.
+ * Rejects if registration fails.
+ * @return {Promise} A Promise that resolves to a GCM registration ID.
+ */
+function getGcmRegistrationId() {
+  return fillFromChromeLocalStorage({gcmRegistrationId: undefined})
+      .then(function(items) {

[robliao, 2015/02/18 00:04:25]

OPTIONAL, since it doesn't really buy that much: Similar restructuring here,
except moving the Promise to capture the async call.

.then(function(items) {
  if (items.gcmRegistrationId) {
    console.log('Reused GCM Registration ID from storage.');
    return Promise.resolve(items.gcmRegistrationId);
  }

  return new Promise(function(resolve, reject) {
    chrome.gcm.register([GCM_PROJECT_ID], function(registrationId) {
      console.log('gcm.register(): ' + registrationId);
      if (registrationId) {
        chrome.storage.local.set({gcmRegistrationId: registrationId});
        resolve(registrationId);
      } else {
        reject();
      }
    });
  });
}

[skare_, 2015/02/19 16:48:10]

Done. Gets rid of an else and some spaces which is nice.

+        return new Promise(function(resolve, reject) {
+          if (items.gcmRegistrationId) {
+            console.log('reused gcm registration id from storage.');
+            resolve(items.gcmRegistrationId);
+          } else {
+            chrome.gcm.register([GCM_PROJECT_ID], function(registrationId) {
+              console.log('gcm.register(): ' + registrationId);
+              if (registrationId) {
+                chrome.storage.local.set({gcmRegistrationId: registrationId});
+                resolve(registrationId);
+              } else {
+                reject();
+              }
+            });
+          }
+        });
+      });
+}