Have FakeGCMProfileService return different registration IDs each time

chrome/browser/services/gcm/fake_gcm_profile_service.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/services/gcm/fake_gcm_profile_service.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 93 matching lines @@
 
 // static
 KeyedService* FakeGCMProfileService::Build(content::BrowserContext* context) {
   Profile* profile = static_cast<Profile*>(context);
   FakeGCMProfileService* service = new FakeGCMProfileService(profile);
   service->SetDriverForTesting(new CustomFakeGCMDriver(service));
   return service;
 }
 
 FakeGCMProfileService::FakeGCMProfileService(Profile* profile)
-    : collect_(false) {
+    : collect_(false),
+      registration_count_(0) {
   static_cast<PushMessagingServiceImpl*>(push_messaging_service())
       ->SetProfileForTesting(profile);
 }
 
 FakeGCMProfileService::~FakeGCMProfileService() {}
 
 void FakeGCMProfileService::RegisterFinished(
     const std::string& app_id,
     const std::vector<std::string>& sender_ids) {
   if (collect_) {
     last_registered_app_id_ = app_id;
     last_registered_sender_ids_ = sender_ids;
   }
 
+  // Generate fake registration IDs with an incrementing count (even for the
+  // same app_id - there's no caching), so tests can distinguish registrations.
+  // The ID also encodes the number of sender IDs which is used by
+  // GcmApiTest.RegisterValidation, but in the most common case of a single
+  // sender ID, this component will be zero (to avoid rebasing existing tests).
+  int registration_id = ++registration_count_ + 1000 * (sender_ids.size() - 1);

[fgorski, 2014/12/08 22:36:59]

why not?
int registration_id = registration_count_ * 1000 + sender_ids.size();
++registration_count_;

I think it is ok to rebase failing tests in that case, but most of them should
stay the same.

[johnme, 2014/12/10 14:12:53]

Ok, I've changed it to a simpler format:
    sender_ids.size() + "-" + (registration_count_++)
and updated the tests.

+
   CustomFakeGCMDriver* custom_driver =
       static_cast<CustomFakeGCMDriver*>(driver());
-  custom_driver->OnRegisterFinished(app_id,
-                           base::UintToString(sender_ids.size()),
-                           GCMClient::SUCCESS);
+  custom_driver->OnRegisterFinished(app_id, base::IntToString(registration_id),
+                                    GCMClient::SUCCESS);
 }
 
 void FakeGCMProfileService::UnregisterFinished(const std::string& app_id) {
   GCMClient::Result result = GCMClient::SUCCESS;
   if (!unregister_responses_.empty()) {
     result = unregister_responses_.front();
     unregister_responses_.pop_front();
   }
 
   CustomFakeGCMDriver* custom_driver =
@@ skipping 22 matching lines @@
     GCMClient::Result result) {
   unregister_responses_.push_back(result);
 }
 
 void FakeGCMProfileService::SetUnregisterCallback(
     const UnregisterCallback& callback) {
   unregister_callback_ = callback;
 }
 
 }  // namespace gcm