mash: Fix system tray clock 12/24 hour time setting

chrome/browser/ui/ash/system_tray_controller_mus.cc

+// 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.
+
+#include "chrome/browser/ui/ash/system_tray_controller_mus.h"
+
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/browser_process_platform_part.h"
+#include "chrome/browser/chromeos/system/system_clock.h"
+#include "content/public/common/mojo_shell_connection.h"
+#include "services/shell/public/cpp/connector.h"
+
+SystemTrayControllerMus::SystemTrayControllerMus() {
+  shell::Connector* connector =
+      content::MojoShellConnection::GetForProcess()->GetConnector();
+  connector->ConnectToInterface("mojo:ash", &system_tray_);
+
+  g_browser_process->platform_part()->GetSystemClock()->AddObserver(this);
+}
+
+SystemTrayControllerMus::~SystemTrayControllerMus() {
+  g_browser_process->platform_part()->GetSystemClock()->RemoveObserver(this);
+}
+
+void SystemTrayControllerMus::OnSystemClockChanged(
+    chromeos::system::SystemClock* clock) {
+  system_tray_->SetUse24HourClock(clock->ShouldUse24HourClock());
+}