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

components/gcm_driver/instance_id/BUILD.gn

Index: components/gcm_driver/instance_id/BUILD.gn
diff --git a/components/gcm_driver/instance_id/BUILD.gn b/components/gcm_driver/instance_id/BUILD.gn
index ec00c0b3766433915e27b9ba8baa1e640e79097c..97f3593db86eda6fb560f47a16a08215e8a728d1 100644
--- a/components/gcm_driver/instance_id/BUILD.gn
+++ b/components/gcm_driver/instance_id/BUILD.gn
@@ -41,6 +41,8 @@ source_set("test_support") {
   sources = [
     "fake_gcm_driver_for_instance_id.cc",
     "fake_gcm_driver_for_instance_id.h",
+    "instance_id_test_utils_android.cc",
+    "instance_id_test_utils_android.h",
   ]
 
   deps = [
@@ -49,6 +51,10 @@ source_set("test_support") {
     "//components/gcm_driver:test_support",
     "//testing/gtest",
   ]
+
+  if (is_android) {
+    deps += [ "android:test_support_jni_headers" ]
+  }
 }
 
 source_set("unit_tests") {