Fix crash in NotificationUIManagerImpl

The profile can be null in the case of "system" notifications.

Bug: 1020555
Change-Id: I80d65c74d4534ed15ffec43c582584fb54559d4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1895378
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711967}

chrome/browser/notifications/notification_ui_manager_browsertest.cc

@@ -122,6 +122,18 @@ IN_PROC_BROWSER_TEST_F(NotificationUIManagerBrowserTest, RetrieveBaseParts) {
   EXPECT_TRUE(message_center());
 }
 
+IN_PROC_BROWSER_TEST_F(NotificationUIManagerBrowserTest, BasicNullProfile) {
+  TestMessageCenterObserver observer;
+  message_center()->AddObserver(&observer);
+  manager()->CancelAll();
+  manager()->Add(CreateTestNotification("hey"), nullptr);
+  EXPECT_EQ(1u, message_center()->NotificationCount());
+  EXPECT_NE("", observer.last_displayed_id());
+  manager()->CancelById("hey", NotificationUIManager::GetProfileID(nullptr));
+  EXPECT_EQ(0u, message_center()->NotificationCount());
+  message_center()->RemoveObserver(&observer);
+}
+
 IN_PROC_BROWSER_TEST_F(NotificationUIManagerBrowserTest, BasicAddCancel) {
   // Someone may create system notifications like "you're in multi-profile
   // mode..." or something which may change the expectation.

chrome/browser/notifications/notification_ui_manager_impl.cc

@@ -88,7 +88,7 @@ void NotificationUIManagerImpl::Add(
       std::make_unique<message_center::Notification>(
           profile_notification->notification()));
 
-  if (profile->IsOffTheRecord())
+  if (profile && profile->IsOffTheRecord())
     observed_otr_profiles_.Add(profile);
 }
 

chrome/browser/notifications/profile_notification.h

@@ -22,7 +22,8 @@ class ProfileNotification {
  public:
   // Returns a string that uniquely identifies a profile + delegate_id pair.
   // The profile_id is used as an identifier to identify a profile instance; it
-  // cannot be NULL. The ID becomes invalid when a profile is destroyed.
+  // can be null for system notifications. The ID becomes invalid when a profile
+  // is destroyed.
   static std::string GetProfileNotificationId(const std::string& delegate_id,
                                               ProfileID profile_id);