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 f2fbd212d833d84a676f69a605ef609bcdcaffe1..5d8de6dc6cbe695e9a444ea603797a498e60a3dd 100644
--- a/components/gcm_driver/instance_id/instance_id_android.cc
+++ b/components/gcm_driver/instance_id/instance_id_android.cc
@@ -24,6 +24,19 @@ using base::android::ConvertUTF8ToJavaString;
 
 namespace instance_id {
 
+InstanceIDAndroid::ScopedBlockOnAsyncTasksForTesting::
+    ScopedBlockOnAsyncTasksForTesting() {
+  JNIEnv* env = AttachCurrentThread();
+  previous_value_ =
+      Java_InstanceIDBridge_setBlockOnAsyncTasksForTesting(env, true);
+}
+
+InstanceIDAndroid::ScopedBlockOnAsyncTasksForTesting::
+    ~ScopedBlockOnAsyncTasksForTesting() {
+  JNIEnv* env = AttachCurrentThread();
+  Java_InstanceIDBridge_setBlockOnAsyncTasksForTesting(env, previous_value_);
+}
+
 // static
 bool InstanceIDAndroid::RegisterJni(JNIEnv* env) {
   return RegisterNativesImpl(env);