Convert now component to use GCM rather than pushMessaging.

chrome/browser/resources/google_now/background.js

Index: chrome/browser/resources/google_now/background.js
diff --git a/chrome/browser/resources/google_now/background.js b/chrome/browser/resources/google_now/background.js
index 087b2ac97912b99ca456bfc1bb2d45d74e1c8676..0d2fba1b49221bbb590548441dde796c24503879 100644
--- a/chrome/browser/resources/google_now/background.js
+++ b/chrome/browser/resources/google_now/background.js
@@ -189,6 +189,7 @@ function areTasksConflicting(newTaskName, scheduledTaskName) {
 var tasks = buildTaskManager(areTasksConflicting);
 
 // Add error processing to API calls.
+wrapper.instrumentChromeApiFunction('gcm.onMessage.addListener', 0);
 wrapper.instrumentChromeApiFunction('metricsPrivate.getVariationParams', 1);
 wrapper.instrumentChromeApiFunction('notifications.clear', 1);
 wrapper.instrumentChromeApiFunction('notifications.create', 2);
@@ -204,10 +205,9 @@ wrapper.instrumentChromeApiFunction(
 wrapper.instrumentChromeApiFunction(
     'notifications.onShowSettings.addListener', 0);
 wrapper.instrumentChromeApiFunction('permissions.contains', 1);
-wrapper.instrumentChromeApiFunction('pushMessaging.onMessage.addListener', 0);
-wrapper.instrumentChromeApiFunction('storage.onChanged.addListener', 0);
 wrapper.instrumentChromeApiFunction('runtime.onInstalled.addListener', 0);
 wrapper.instrumentChromeApiFunction('runtime.onStartup.addListener', 0);
+wrapper.instrumentChromeApiFunction('storage.onChanged.addListener', 0);
 wrapper.instrumentChromeApiFunction('tabs.create', 1);
 
 var updateCardsAttempts = buildAttemptManager(
@@ -1015,6 +1015,7 @@ function stopPollingCards() {
  */
 function initialize() {
   recordEvent(GoogleNowEvent.EXTENSION_START);
+  registerForGcm();
   onStateChange();
 }
 
@@ -1334,13 +1335,15 @@ instrumented.storage.onChanged.addListener(function(changes, areaName) {
   }
 });
 
-instrumented.pushMessaging.onMessage.addListener(function(message) {
-  // message.payload will be '' when the extension first starts.
-  // Each time after signing in, we'll get latest payload for all channels.
-  // So, we need to poll the server only when the payload is non-empty and has
-  // changed.
-  console.log('pushMessaging.onMessage ' + JSON.stringify(message));
-  if (message.payload.indexOf('REQUEST_CARDS') == 0) {
+instrumented.gcm.onMessage.addListener(function(message) {
+  console.log('gcm.onMessage ' + JSON.stringify(message));
+  if (!message || !message.data) {
+    return;
+  }
+
+  var payload = message.data.payload;
+  var subchannel = message.data.subchannelId;

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

So we still need subchannel ID? I thought subchannel Ids were an artifact of
Chrome Push Messaging and aren't needed for Android style GCM. Maybe we can
transform this into some sort of tag instead.

If we still need this, keep this as 'var subchannelId' for consistency.

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

made this 'tag' - I also don't think we'll need it, could remove if desired. let
me know.

+  if (payload.indexOf('REQUEST_CARDS') == 0) {
     tasks.add(ON_PUSH_MESSAGE_START_TASK_NAME, function() {
       // Accept promise rejection on failure since it's safer to do nothing,
       // preventing polling the server when the payload really didn't change.
@@ -1349,9 +1352,8 @@ instrumented.pushMessaging.onMessage.addListener(function(message) {
         /** @type {Object<string, StoredNotificationGroup>} */
         notificationGroups: {}
       }, PromiseRejection.ALLOW).then(function(items) {
-        if (items.lastPollNowPayloads[message.subchannelId] !=
-            message.payload) {
-          items.lastPollNowPayloads[message.subchannelId] = message.payload;
+        if (items.lastPollNowPayloads[message.subchannelId] != payload) {

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

message.subchannelId -> subchannelId
Two more instances below.

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

Done.

+          items.lastPollNowPayloads[message.subchannelId] = payload;
 
           items.notificationGroups['PUSH' + message.subchannelId] = {
             cards: [],