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

components/gcm_driver/instance_id/scoped_use_fake_instance_id_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_SCOPED_USE_FAKE_INSTANCE_ID_ANDROID_H_
+#define COMPONENTS_GCM_DRIVER_INSTANCE_ID_SCOPED_USE_FAKE_INSTANCE_ID_ANDROID_H_
+
+#include <jni.h>
+
+#include "base/macros.h"
+
+namespace instance_id {
+
+// Tests depending on InstanceID must use this, to avoid hitting the
+// network/disk. Also clears cached InstanceIDs when constructed/destructed.
+class ScopedUseFakeInstanceIDAndroid {
+ public:
+  ScopedUseFakeInstanceIDAndroid();
+  ~ScopedUseFakeInstanceIDAndroid();
+
+  // Register JNI methods.
+  static bool RegisterJni(JNIEnv* env);
+
+ private:
+  bool previous_value_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedUseFakeInstanceIDAndroid);
+};
+
+}  // namespace instance_id
+
+#endif  // COMPONENTS_GCM_DRIVER_INSTANCE_ID_SCOPED_USE_FAKE_INSTANCE_ID_ANDROID_H_