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

components/gcm_driver/instance_id/instance_id_android.cc

Index: components/gcm_driver/instance_id/instance_id_android.cc
diff --git a/components/gcm_driver/instance_id/instance_id_android.cc b/components/gcm_driver/instance_id/instance_id_android.cc
index 29e4629f6025d6bd82f6bfda9130ddf94a72a51d..3a72b0865ee691c08d463dafd7f65a0db831722c 100644
--- a/components/gcm_driver/instance_id/instance_id_android.cc
+++ b/components/gcm_driver/instance_id/instance_id_android.cc
@@ -27,6 +27,12 @@ bool InstanceIDAndroid::RegisterBindings(JNIEnv* env) {
 }
 
 // static
+void InstanceIDAndroid::ClearDataAndSetUseFakeForTesting(bool use_fake) {
+  JNIEnv* env = AttachCurrentThread();
+  Java_InstanceIDWithSubtype_clearDataAndSetUseFakeForTesting(env, use_fake);
+}
+
+// static
 scoped_ptr<InstanceID> InstanceID::Create(const std::string& app_id,
                                           gcm::InstanceIDHandler* unused) {
   return make_scoped_ptr(new InstanceIDAndroid(app_id));