Hook up system clock update dbus signal to chrome and ash tray ui.

chrome/browser/chromeos/system/ash_system_tray_delegate.cc

Index: chrome/browser/chromeos/system/ash_system_tray_delegate.cc
diff --git a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
index caba910ee4cc548a5ee8f4f8c5743156c2bb7630..9d6afaa672731132e4d98c1197246f9f8a01217b 100644
--- a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
+++ b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
@@ -82,6 +82,7 @@
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/power_manager_client.h"
 #include "chromeos/dbus/session_manager_client.h"
+#include "chromeos/dbus/system_clock_client.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_service.h"
@@ -197,6 +198,7 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
                            public content::NotificationObserver,
                            public input_method::InputMethodManager::Observer,
                            public system::TimezoneSettings::Observer,
+                           public chromeos::SystemClockClient::Observer,
                            public device::BluetoothAdapter::Observer,
                            public SystemKeyEventListener::CapsLockObserver,
                            public ash::NetworkTrayDelegate,
@@ -265,6 +267,7 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
     input_method::GetInputMethodManager()->AddObserver(this);
 
     system::TimezoneSettings::GetInstance()->AddObserver(this);
+    DBusThreadManager::Get()->GetSystemClockClient()->AddObserver(this);

[stevenjb, 2013/03/13 17:34:31]

What do you think of making TrayClock a SystemClockClient::Observer instead of
using the delegate? Eventually we want to move TimezoneSettings into
src/chromeos also and remove ClockObserver entirely. This means moving TrayClock
into ash/system/chromeos, which seems fine.

[jennyz, 2013/03/13 19:14:02]

I am not sure if TrayDate is chromeos only, or will it be used on other aura
enabled platform as well? If it is chromeos only, it makes sense to move it to
ash/system/chromeos and have it be chromeos::SystemClockClient::Observer. Can we
defer this task to a separate refactor bug? This is to fix the P1 bug which has
been lingering for a long time and needs to be ported back to R26.

[stevenjb, 2013/03/13 19:22:39]

So, TrayClock is already effectively chromeos specific, since as near as I can
tell system::TimezoneSettings is chromeos-only, as is SystemClockClient. If/when
we want to add one for other platforms we would rename the existing one as
TrayClockChromeos and add TrayClockWindows (or whatever), possibly with a common
TrayClock interface. We still shouldn't be calling into Chrome for OS specific
calls.

That said, if you would rather that be done in a separate pass I am OK with
that, but we are making additional work for ourselves later.

[jennyz, 2013/03/13 20:47:16]

I need to jump to audio work for M27. I filed crbug.com/190299 for the work
item, I will take this work when I got the audio work done. Thanks!

 
     if (SystemKeyEventListener::GetInstance())
       SystemKeyEventListener::GetInstance()->AddCapsLockObserver(this);
@@ -313,6 +316,7 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
       audiohandler->RemoveVolumeObserver(this);
     DBusThreadManager::Get()->GetSessionManagerClient()->RemoveObserver(this);
     DBusThreadManager::Get()->GetPowerManagerClient()->RemoveObserver(this);
+    DBusThreadManager::Get()->GetSystemClockClient()->RemoveObserver(this);
     NetworkLibrary* crosnet = CrosLibrary::Get()->GetNetworkLibrary();
     if (crosnet)
       crosnet->RemoveNetworkManagerObserver(this);
@@ -1307,6 +1311,11 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
     GetSystemTrayNotifier()->NotifyRefreshClock();
   }
 
+  // Overridden from SystemClockClient::Observer.
+  virtual void SystemClockUpdated() OVERRIDE {
+    GetSystemTrayNotifier()->NotifySystemClockTimeUpdated();
+  }
+
   // Overridden from BluetoothAdapter::Observer.
   virtual void AdapterPresentChanged(device::BluetoothAdapter* adapter,
                                      bool present) OVERRIDE {