Filter out ARC notifiers that are not shown in launcher.

chrome/browser/notifications/arc_application_notifier_source_chromeos.cc

Index: chrome/browser/notifications/arc_application_notifier_source_chromeos.cc
diff --git a/chrome/browser/notifications/arc_application_notifier_source_chromeos.cc b/chrome/browser/notifications/arc_application_notifier_source_chromeos.cc
index 108a74cbf30dd5a7d23c7812afce7f7e3cfcd6a6..8ab57134142872d6a6348e091f0f33877ccc73ac 100644
--- a/chrome/browser/notifications/arc_application_notifier_source_chromeos.cc
+++ b/chrome/browser/notifications/arc_application_notifier_source_chromeos.cc
@@ -8,6 +8,7 @@
 
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/app_list/arc/arc_app_utils.h"
 #include "ui/base/layout.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
@@ -46,7 +47,7 @@ ArcApplicationNotifierSourceChromeOS::GetNotifierList(Profile* profile) {
 
   for (const std::string& app_id : app_ids) {
     const auto app = app_list->GetApp(app_id);
-    if (!app)
+    if (!app || !arc::ShouldShowInLauncher(app_id))

[dewittj, 2016/06/27 16:17:49]

Can an app that's not in the launcher show notifications?

[uekawa-, 2016/06/27 23:15:09]

There are  launchable activities and other activities, app_list->GetApp() seems
to be obtaining the list of launchable activities.

hmmm.. is this right?

[hirono, 2016/06/28 02:20:31]

I think there is two points here.

First the notifications enabled flag is set for packages in Android side. So if
the package has at least one launchable acitvity, users can control the
notifications flag for the package. Users cannot block notifications from
packages that have no launchable activity (e.g. ContentProvider that shows
notifications) but I guess the number of such package is small.

Second arc::ShouldShowInLauncher filter out activities that are launchable but
we would not like to show in Chrome launcher. Currently it hides only Android
Settings application.

Android UI does not allow to block notifications from Settings app since it's
system app. So I'd like to remove Android Settings application from notifier
list. Now I have two plans here.

a. Use arc::ShouldShowInLauncher to filter out Settings applications since
arc::ShouldShowInLauncher is almost used to filter out launch-able system
applications. 
b. Add is_system flag to application info and filter out all system applications
from notifier list.

WDYT?

[dewittj, 2016/06/29 16:09:34]

I am not sure if you are waiting for me or not.  If you ware waiting for me, at
this layer I would love to see a function
arc::UserCanControlNotifierSettings(app_id) or something whose purpose is
obvious.  Then at the ARC layer you can implement it however you like.

       continue;
     // Handle packages having multiple launcher activities.
     if (package_to_app_ids_.count(app->package_name))