Support SystemTrayDelegate::ShowPowerSettings() in mustash

ash/mus/system_tray_delegate_mus.cc

Index: ash/mus/system_tray_delegate_mus.cc
diff --git a/ash/mus/system_tray_delegate_mus.cc b/ash/mus/system_tray_delegate_mus.cc
index 6d390b7d76efc4de6101525e521e78d73adbe2c7..1c520240cadfc39bd8f70277607e5e07391cfc00 100644
--- a/ash/mus/system_tray_delegate_mus.cc
+++ b/ash/mus/system_tray_delegate_mus.cc
@@ -79,8 +79,7 @@ void SystemTrayDelegateMus::ShowDisplaySettings() {
 }
 
 void SystemTrayDelegateMus::ShowPowerSettings() {
-  // http://crbug.com/647412
-  NOTIMPLEMENTED();
+  ConnectToSystemTrayClient()->ShowPowerSettings();

[michaelpg, 2016/09/28 23:09:15]

does this mean power_handler.cc be updated as well to support mash?
https://cs.chromium.org/chromium/src/chrome/browser/ui/webui/options/chromeos...

If not, then this would just open Settings for no reason.

[James Cook, 2016/09/29 15:28:29]

Yes, power_handler.cc will need to be updated to support mash, but I would
prefer to do that in a separate CL. Updating PowerHandler will require
initializing PowerStatus in the ash process, which will trigger additional D-Bus
traffic to powerd via PowerManagerClient. I am not completely certain that I can
do that safely with PowerStatus as it exists today. See discussion in
crbug.com/644348

Right now under mash this CL opens battery status with battery info at 50%,
which I suspect is just hard-coded into the HTML as the default. It doesn't
update, but it does open something.

If you would prefer me to wait on this CL until PowerStatus is sorted out I'm
happy to do that.

[michaelpg, 2016/09/29 17:00:51]

The only reason to open Settings from the notification (and the only reason to
show the notification) is to give the user the ability to change power source.

On the other hand, I guess this is better than a NOTIMPLEMENTED(). So I'll leave
it up to you what order you want to land things in.

 }
 
 void SystemTrayDelegateMus::ShowChromeSlow() {