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

components/gcm_driver.gypi

Index: components/gcm_driver.gypi
diff --git a/components/gcm_driver.gypi b/components/gcm_driver.gypi
index 38685d528824db67c5a3138f4e5c5f96243ad677..5c919e612dd03a64171956ccf4a8a589633b338f 100644
--- a/components/gcm_driver.gypi
+++ b/components/gcm_driver.gypi
@@ -215,6 +215,13 @@
         'gcm_driver/instance_id/fake_gcm_driver_for_instance_id.cc',
         'gcm_driver/instance_id/fake_gcm_driver_for_instance_id.h',
       ],
+      'conditions': [
+        ['OS == "android"', {
+          'dependencies': [
+            'instance_id_driver_test_support_jni_headers',
+          ],
+        }],
+      ],
     },
     {
       # GN version: //components/gcm_driver/crypto
@@ -339,6 +346,18 @@
           'includes': [ '../build/java.gypi' ],
         },
         {
+          # GN version: //components/gcm_driver/instance_id/android:instance_id_driver_test_support_java
+          'target_name': 'instance_id_driver_test_support_java',
+          'type': 'none',
+          'dependencies': [
+            'instance_id_driver_java',
+          ],
+          'variables': {
+            'java_in_dir': 'gcm_driver/instance_id/android/javatests',
+          },
+          'includes': [ '../build/java.gypi' ],
+        },
+        {
           # GN version: //components/gcm_driver/instance_id/android:jni_headers
           'target_name': 'instance_id_driver_jni_headers',
           'type': 'none',
@@ -350,6 +369,18 @@
           },
           'includes': [ '../build/jni_generator.gypi' ],
         },
+        {
+          # GN version: //components/gcm_driver/instance_id/android:test_support_jni_headers
+          'target_name': 'instance_id_driver_test_support_jni_headers',
+          'type': 'none',
+          'sources': [
+            'gcm_driver/instance_id/android/javatests/src/org/chromium/components/gcm_driver/instance_id/FakeInstanceIDWithSubtype.java',
+          ],
+          'variables': {
+            'jni_gen_package': 'components/gcm_driver/instance_id',
+          },
+          'includes': [ '../build/jni_generator.gypi' ],
+        },
       ],
      },
     ],