cros: Convert SystemTrayDelegate::ManageBluetoothDevices to mojo for mash

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
index 99ba17e61be7759633428d665360622f473a3084..65046057140468cac34ad4d88aa38483c30435fb 100644
--- a/ash/public/interfaces/system_tray.mojom
+++ b/ash/public/interfaces/system_tray.mojom
@@ -5,6 +5,7 @@
 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.
 interface SystemTray {
@@ -34,6 +35,18 @@ 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,

[James Cook, 2017/03/17 22:23:30]

This method isn't called yet, but is used to generate the function signature in
SystemTrayClient() that I'll need in the next CL.

[msw, 2017/03/18 00:44:44]

Acknowledged.

+                             mojo.common.mojom.String16 name_for_display,
+                             bool paired,

[James Cook, 2017/03/17 22:23:30]

I do not know why you would show a pairing dialog if |paired| was true, but
that's how it works today.

[msw, 2017/03/18 00:44:44]

Acknowledged.

+                             bool connected);
+
   // Shows the settings related to date, timezone etc.
   ShowDateSettings();