Add update available icon in system tray

ash/public/interfaces/system_tray.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module ash.mojom;
 
 import "ash/public/interfaces/update.mojom";
 import "mojo/common/string16.mojom";
 
 // Allows clients (e.g. Chrome browser) to control the ash system tray menu.
@@ skipping 16 matching lines @@
   // enterprise management. The item appears if |enterprise_domain| is not empty
   // or |active_directory_managed| is true.
   SetEnterpriseDomain(string enterprise_domain, bool active_directory_managed);
 
   // Shows an icon in the system tray indicating that a software update is
   // available. Once shown the icon persists until reboot. |severity| and
   // |factory_reset_required| are used to set the icon, color, and tooltip.
   ShowUpdateIcon(UpdateSeverity severity,
                  bool factory_reset_required,
                  UpdateType update_type);
+
+  // Shows an icon in the system tray indicating that a software update is
+  // available but user's agreement is required as current connection is
+  // cellular. Once shown the icon persists until reboot.
+  ShowUpdateOverCellularAvailableIcon();
 };
 
 // Allows ash system tray to control a client (e.g. Chrome browser). Requests
 // often involve preferences or web UI that is not available to ash.
 interface SystemTrayClient {
   // Shows general settings UI.
   ShowSettings();
 
   // Shows settings related to Bluetooth devices (e.g. to add a device).
   ShowBluetoothSettings();
 
   // Shows the web UI dialog to pair a Bluetooth device.
   // |address| is the unique device address in the form "XX:XX:XX:XX:XX:XX"
   // with hex digits X. |name_for_display| is a human-readable name, not
   // necessarily the device name.
   ShowBluetoothPairingDialog(string address,
                              mojo.common.mojom.String16 name_for_display,
                              bool paired,
                              bool connected);
 
   // Shows the settings related to date, timezone etc.
   ShowDateSettings();
 
+  // Show the about chrome OS page.
+  ShowAboutChromeOS();

[stevenjb, 2017/05/15 18:06:45]

nit: Put this next to 'ShowHelp', and update the comments as follows. 

// Show the 'About Chrome OS' page in the Settings UI.
ShowAboutChromeOS();

// Show the Chromebook help app.
ShowHelp();

(The difference between 'help' and 'about' is often confused, e.g. even though
the Settings page is 'About Chrome OS', the URL for it is (for historical
reasons) chrome://settings/help. That's why I want to clarify these here.)

[weidongg, 2017/05/16 19:46:08]

Done.

+
   // Shows the dialog to set system time, date, and timezone.
   ShowSetTimeDialog();
 
   // Shows settings related to multiple displays.
   ShowDisplaySettings();
 
   // Shows settings related to power.
   ShowPowerSettings();
 
   // Shows the page that lets you disable performance tracing.
@@ skipping 44 matching lines @@
 
   // Shows UI for changing proxy settings.
   ShowProxySettings();
 
   // Attempts to sign out the user.
   // TODO(jamescook): Migrate to a user or login service. crbug.com/665582
   SignOut();
 
   // Attempts to restart the system for update.
   RequestRestartForUpdate();
+
+  // Attempts to check for update;
+  RequestUpdateCheck();
 };