Add device policy: Kiosk Virtual Keyboard Layout.

chrome/browser/chromeos/policy/proto/chrome_device_policy.proto

Index: chrome/browser/chromeos/policy/proto/chrome_device_policy.proto
diff --git a/chrome/browser/chromeos/policy/proto/chrome_device_policy.proto b/chrome/browser/chromeos/policy/proto/chrome_device_policy.proto
index 180b57bdf4db2ab4879123fec13d86cc95850058..7430601fb06e28f8c7d76ec188dd53b87826aaa5 100644
--- a/chrome/browser/chromeos/policy/proto/chrome_device_policy.proto
+++ b/chrome/browser/chromeos/policy/proto/chrome_device_policy.proto
@@ -121,6 +121,13 @@ message AppPackProto {
   repeated AppPackEntryProto app_pack = 1;
 }
 
+message KioskVirtualKeyboardProto {
+  // This is a special policy for kiosk mode that specifies whether the virtual
+  // keyboard should always be enabled. If non-null this should be a valid
+  // keyboard layout.
+  optional string layout = 1;
+}
+
 // This is a special policy for kiosk/retail mode that specifies what apps
 // should be pinned to the launcher. For regular accounts, pinned apps are
 // controlled through user policy.
@@ -606,4 +613,5 @@ message ChromeDeviceSettingsProto {
   optional SystemUse24HourClockProto use_24hour_clock = 30;
   optional AutoCleanupSettigsProto auto_clean_up_settings = 31;
   optional SystemSettingsProto system_settings = 32;
+  optional KioskVirtualKeyboardProto kiosk_virtual_keyboard = 33;
 }