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

components/gcm_driver/instance_id/instance_id_driver_unittest.cc

Index: components/gcm_driver/instance_id/instance_id_driver_unittest.cc
diff --git a/components/gcm_driver/instance_id/instance_id_driver_unittest.cc b/components/gcm_driver/instance_id/instance_id_driver_unittest.cc
index 8997296aca9b1dad49e6749524421ca3094672b6..018f654be1f80dd32dbc62f47b99fdc338775879 100644
--- a/components/gcm_driver/instance_id/instance_id_driver_unittest.cc
+++ b/components/gcm_driver/instance_id/instance_id_driver_unittest.cc
@@ -15,8 +15,13 @@
 #include "base/strings/string_util.h"
 #include "components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.h"
 #include "components/gcm_driver/instance_id/instance_id.h"
+#include "components/gcm_driver/instance_id/instance_id_test_utils_android.h"

[Peter Beverloo, 2016/04/15 00:00:18]

Stick this in the #ifdef too?

[johnme, 2016/04/15 16:00:43]

Done.

 #include "testing/gtest/include/gtest/gtest.h"
 
+#if defined(OS_ANDROID)
+#include "components/gcm_driver/instance_id/instance_id_android.h"
+#endif  // OS_ANDROID
+
 namespace instance_id {
 
 namespace {
@@ -105,6 +110,10 @@ InstanceIDDriverTest::~InstanceIDDriverTest() {
 }
 
 void InstanceIDDriverTest::SetUp() {
+#if defined(OS_ANDROID)
+  InstanceIDTestUtilsAndroid::ClearDataAndSetUseFakeForTesting(true);
+  InstanceIDAndroid::SetBlockOnAsyncTasksForTesting(true);

[Peter Beverloo, 2016/04/15 00:00:17]

Clean up as part of TearDown? They're statics so this could have side-effects
for other tests ran as part of the same process too.

[johnme, 2016/04/15 16:00:43]

Done (I'd been hoping to avoid the boilerplate, as it's never wrong for tests to
run with these statics enabled, but it might cause people to forget to enable
them in other tests, so fair enough).

+#endif  // OS_ANDROID
   gcm_driver_.reset(new FakeGCMDriverForInstanceID);
   RecreateInstanceIDDriver();
 }