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

ash/public/interfaces/system_tray.mojom

Index: ash/public/interfaces/system_tray.mojom
diff --git a/ash/public/interfaces/system_tray.mojom b/ash/public/interfaces/system_tray.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..14c4f949e7b33ef3c662cc75469c68c2c8e4d071
--- /dev/null
+++ b/ash/public/interfaces/system_tray.mojom
@@ -0,0 +1,14 @@
+// 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;
+
+// Allows clients (e.g. Chrome browser) to control the ash system tray menu.
+interface SystemTray {

[James Cook, 2016/09/19 22:51:38]

Do we have a naming convention for these things? msw was using ShelfController
and WallpaperController. I suspect that was because just "Shelf" is generic and
there are shelf-y controller classes in //chrome. But that feels odd to me,
since mojom.ShelfController is implemented by ShelfDelegateMus, not some kind of
ControllerImpl. Should I stick with this, or switch to SystemTrayController for
consistency?

[James Cook, 2016/09/20 01:52:11]

Ping?

[sky, 2016/09/20 02:45:16]

Sorry, somehow missed your question. One naming convention we've gone with is
Foo and FooClient. You can see that in WindowTree and WindowTreeClient. As you
pointed out we aren't particularly consistent in ash code yet. I don't feel
strongly here. I'm fine with SystemTray.

+  // Sets the clock to use 24 hour time formatting if |use_24_hour| is true.
+  // Otherwise sets 12 hour time formatting.
+  SetUse24HourClock(bool use_24_hour);
+};
+
+// TODO(jamescook): SystemTrayDelegate to communicate from ash to chrome.