[IME] migrate the xkb ID to extension based xkb ID.

chromeos/ime/extension_ime_util.cc

Index: chromeos/ime/extension_ime_util.cc
diff --git a/chromeos/ime/extension_ime_util.cc b/chromeos/ime/extension_ime_util.cc
index 7955e52536caae6569ca3c4a917fb6f66e25ab55..98f42ee9c2f98d2c90a1a20103e92e7a8b63293b 100644
--- a/chromeos/ime/extension_ime_util.cc
+++ b/chromeos/ime/extension_ime_util.cc
@@ -52,6 +52,14 @@ std::string GetExtensionIDFromInputMethodID(
   return "";
 }
 
+std::string GetInputMethodIDByKeyboardLayout(
+    const std::string& keyboard_layout_id) {
+  if (IsKeyboardLayoutExtension(keyboard_layout_id))
+    return keyboard_layout_id;
+  DCHECK(StartsWithASCII(keyboard_layout_id, "xkb:", true));
+  return kExtensionXkbIdPrefix + keyboard_layout_id;
+}
+
 bool IsExtensionIME(const std::string& input_method_id) {
   return StartsWithASCII(input_method_id,
                          kExtensionIMEPrefix,