Add fake for InstanceIDWithSubtype.java, in order to re-use unit test

components/gcm_driver/instance_id/instance_id_test_utils_android.h

+// 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.
+
+#ifndef COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_TEST_UTILS_ANDROID_H_
+#define COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_TEST_UTILS_ANDROID_H_
+
+#include <jni.h>
+
+#include "base/macros.h"
+
+namespace instance_id {
+
+class InstanceIDTestUtilsAndroid {
+ public:
+  // Register JNI methods.
+  static bool RegisterJni(JNIEnv* env);
+
+  // Tests depending on InstanceID must enable this, to avoid hitting the
+  // network/disk. Reset it to false when tearing down.
+  static void ClearDataAndSetUseFakeForTesting(bool use_fake);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(InstanceIDTestUtilsAndroid);
+};
+
+}  // namespace instance_id
+
+#endif  // COMPONENTS_GCM_DRIVER_INSTANCE_ID_INSTANCE_ID_TEST_UTILS_ANDROID_H_