Handle unknown version invalidations in DriveNotificationManager.

Not all invalidations for Drive come with a version, so check
is_unknown_version().

Bug: 870004
Change-Id: I4640f65883fc858fe98404dd9c6c74d3313ac03e
Reviewed-on: https://chromium-review.googlesource.com/c/1290449Reviewed-by: Stuart Langley <slangley@chromium.org>
Commit-Queue: Sam McNally <sammc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601012}

components/drive/drive_notification_manager.cc

@@ -109,7 +109,8 @@ void DriveNotificationManager::OnIncomingInvalidation(
     auto invalidations = invalidation_map.ForObject(id);
     int64_t& invalidation_version = invalidated_change_ids_[unpacked_id] = -1;
     for (auto& invalidation : invalidations) {
-      if (invalidation.version() > invalidation_version) {
+      if (!invalidation.is_unknown_version() &&
+          invalidation.version() > invalidation_version) {
         invalidation_version = invalidation.version();
       }
     }

components/drive/drive_notification_manager_unittest.cc

@@ -159,13 +159,13 @@ TEST_F(DriveNotificationManagerTest, TestBatchInvalidation) {
   // Emitting an invalidation should not call our observer until the timer
   // expires.
   fake_invalidation_service_->EmitInvalidationForTest(
-      syncer::Invalidation::Init(kDefaultCorpusObjectId, 1, ""));
+      syncer::Invalidation::InitUnknownVersion(kDefaultCorpusObjectId));
   EXPECT_TRUE(drive_notification_observer_->GetNotificationIds().empty());
 
   task_runner_->FastForwardBy(base::TimeDelta::FromSeconds(5));
 
   // Default corpus is has the id "" when sent to observers.
-  std::map<std::string, int64_t> expected_ids = {{"", 1}};
+  std::map<std::string, int64_t> expected_ids = {{"", -1}};
   EXPECT_EQ(expected_ids, drive_notification_observer_->GetNotificationIds());
   drive_notification_observer_->ClearNotificationIds();