Restoring notifications on startup

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 da293eaaf19e29c258896a91f6a69ccff6a4a0c0..98651bab5f283aa9d0befe0329f20336c1cd22be 100644
--- a/chrome/browser/resources/google_now/background.js
+++ b/chrome/browser/resources/google_now/background.js
@@ -20,7 +20,6 @@
 // TODO(vadimt): Decide what to do in incognito mode.
 // TODO(vadimt): Figure out the final values of the constants.
 // TODO(vadimt): Remove 'console' calls.
-// TODO(vadimt): Consider sending JS stacks for malformed server responses.
 
 /**
  * Standard response code for successful HTTP requests. This is the only success
@@ -81,6 +80,7 @@ var UPDATE_CARDS_TASK_NAME = 'update-cards';
 var DISMISS_CARD_TASK_NAME = 'dismiss-card';
 var RETRY_DISMISS_TASK_NAME = 'retry-dismiss';
 var STATE_CHANGED_TASK_NAME = 'state-changed';
+var SHOW_ON_START_TASK_NAME = 'show-cards-on-start';
 
 var LOCATION_WATCH_NAME = 'location-watch';
 
@@ -317,8 +317,6 @@ function showNotificationCards(cards) {
                 previousVersion);
           }
 
-          recordEvent(GoogleNowEvent.CARDS_PARSE_SUCCESS);
-
           chrome.storage.local.set({
             notificationsData: newNotificationsData,
             recentDismissals: updatedRecentDismissals
@@ -447,6 +445,21 @@ function scheduleNextPoll(groups) {
 }
 
 /**
+ * Merges notification groups into a set of Chrome notifications and shows them.
+ * @param {Object.<string, StorageGroup>} notificationGroups Map from group name
+ *     to group information.
+ */
+function mergeAndShowNotificationCards(notificationGroups) {
+  // Merge cards from all groups into one set.

[rgustafson, 2013/10/15 21:14:33]

nit: comment not really necessary. If you want more detail, put it in the
function comment since this is describing the whole function minus
showNotificationCards which is self explanatory.

[vadimt, 2013/10/15 21:28:03]

Done.

+  var mergedCards = {};
+
+  for (var groupName in notificationGroups)
+    mergeGroup(mergedCards, notificationGroups[groupName]);
+
+  showNotificationCards(mergedCards);
+}
+
+/**
  * Parses JSON response from the notification server, shows notifications and
  * schedules next update.
  * @param {string} response Server response.
@@ -455,13 +468,13 @@ function parseAndShowNotificationCards(response) {
   console.log('parseAndShowNotificationCards ' + response);
   var parsedResponse = JSON.parse(response);
 
-  var groups = parsedResponse.groups;
+  var receivedGroups = parsedResponse.groups;
 
   // Populate groups with corresponding cards.
   if (parsedResponse.notifications) {
     for (var i = 0; i != parsedResponse.notifications.length; ++i) {
       var card = parsedResponse.notifications[i];
-      var group = groups[card.groupName];
+      var group = receivedGroups[card.groupName];
       group.cards = group.cards || [];
       group.cards.push(card);
     }
@@ -474,12 +487,9 @@ function parseAndShowNotificationCards(response) {
 
     var now = Date.now();
 
-    // Build updated set of groups and merge cards from all groups into one set.
-    var updatedGroups = {};

[rgustafson, 2013/10/15 21:14:33]

For updatedGroups -> items.notificationGroups

What if a group disappears? 

[vadimt, 2013/10/15 21:28:03]

Ah, looks like I forgot the protocol...
So, the server will send all existing groups, always, correct?

[rgustafson, 2013/10/15 21:43:41]

This is the joy of having extensibility which there are no plans to use. :) With
the existing server implementation, all groups will always be sent so this would
be fine. If we were to add more groups with more specific requests, those would
likely only exist for the lifetime of one notification or less. There is a less
than one percent chance imo of another group being made which behaves in the
exact same way as the existing groups; new groups would be transient. It's up to
you how far you want to go with making this extensible since I really do not see
this being used any time soon.

[vadimt, 2013/10/15 22:05:36]

Thanks; you've found a regression; I'm fixing it.

-    var mergedCards = {};
-
-    for (var groupName in groups) {
-      var receivedGroup = groups[groupName];
+    // Build updated set of groups.
+    for (var groupName in receivedGroups) {
+      var receivedGroup = receivedGroups[groupName];
       var storageGroup = items.notificationGroups[groupName] || {
         cards: [],
         cardsTimestamp: undefined,
@@ -501,16 +511,13 @@ function parseAndShowNotificationCards(response) {
             now + receivedGroup.nextPollSeconds * MS_IN_SECOND;
       }
 
-      updatedGroups[groupName] = storageGroup;
-
-      mergeGroup(mergedCards, storageGroup);
+      items.notificationGroups[groupName] = storageGroup;
     }
 
-    scheduleNextPoll(updatedGroups);
-
-    chrome.storage.local.set({notificationGroups: updatedGroups});
-
-    showNotificationCards(mergedCards);
+    scheduleNextPoll(items.notificationGroups);
+    chrome.storage.local.set({notificationGroups: items.notificationGroups});
+    mergeAndShowNotificationCards(items.notificationGroups);
+    recordEvent(GoogleNowEvent.CARDS_PARSE_SUCCESS);
   });
 }
 
@@ -876,12 +883,6 @@ function stopPollingCards() {
  */
 function initialize() {
   recordEvent(GoogleNowEvent.EXTENSION_START);
-
-  // Alarms persist across chrome restarts. This is undesirable since it
-  // prevents us from starting up everything (alarms are a heuristic to
-  // determine if we are already running). To mitigate this, we will
-  // shut everything down on initialize before starting everything up.
-  stopPollingCards();
   onStateChange();
 }
 
@@ -1085,6 +1086,20 @@ instrumented.runtime.onInstalled.addListener(function(details) {
 
 instrumented.runtime.onStartup.addListener(function() {
   console.log('onStartup');
+
+  // Show notifications received by earlier polls. Doing this as early as
+  // possible to reduce latency of showing first notifications. This mimics how
+  // persistent notifications will work.
+  tasks.add(SHOW_ON_START_TASK_NAME, function() {
+    instrumented.storage.local.get('notificationGroups', function(items) {
+      console.log('onStartup-get ' + JSON.stringify(items));
+      items = items || {};
+      items.notificationGroups = items.notificationGroups || {};
+
+      mergeAndShowNotificationCards(items.notificationGroups);
+    });
+  });
+
   initialize();
 });