Have FakeGCMProfileService return different registration IDs each time

chrome/browser/services/gcm/fake_gcm_profile_service.h

Index: chrome/browser/services/gcm/fake_gcm_profile_service.h
diff --git a/chrome/browser/services/gcm/fake_gcm_profile_service.h b/chrome/browser/services/gcm/fake_gcm_profile_service.h
index fe2ffd8cbf6bc1b9a5caf19da9070c79a2c6b707..58ba184ceefdb073f4d396b2f84b4c07dda2a9f8 100644
--- a/chrome/browser/services/gcm/fake_gcm_profile_service.h
+++ b/chrome/browser/services/gcm/fake_gcm_profile_service.h
@@ -64,6 +64,9 @@ class FakeGCMProfileService : public GCMProfileService {
   // Indicates whether the service will collect paramters of the calls for
   // furter verification in tests.
   bool collect_;
+  // Used to give each registration a unique registration id. Does not decrease
+  // when unregister is called.
+  int registration_count_;
   std::string last_registered_app_id_;
   std::vector<std::string> last_registered_sender_ids_;
   std::list<GCMClient::Result> unregister_responses_;