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..e19a7cd0b9acac09c95e40db3062627625dc3431 100644
--- a/components/gcm_driver/instance_id/BUILD.gn
+++ b/components/gcm_driver/instance_id/BUILD.gn
@@ -64,4 +64,11 @@ source_set("unit_tests") {
     "//google_apis/gcm",
     "//testing/gtest",
   ]
+
+  if (is_android) {
+    deps += [
+      # Just for NestedMessagePumpAndroid (and NestedSystemMessageHandler).
+      "//content/test:layouttest_support",
+    ]
+  }
 }