Sync: Support multiple setup UIs.

components/sync_driver/sync_service.cc

 // Copyright 2015 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 "components/sync_driver/sync_service.h"
 
 #include "google_apis/gaia/google_service_auth_error.h"
 #include "sync/internal_api/public/sync_manager.h"
 
 namespace sync_driver {
 
+SyncSetupInProgressHandle::SyncSetupInProgressHandle(base::Closure on_destroy)
+    : on_destroy_(on_destroy) {}
+
+SyncSetupInProgressHandle::~SyncSetupInProgressHandle() {
+  on_destroy_.Run();
+}
+
 SyncService::SyncTokenStatus::SyncTokenStatus()
     : connection_status(syncer::CONNECTION_NOT_ATTEMPTED),
       last_get_token_error(GoogleServiceAuthError::AuthErrorNone()) {}
-SyncService::SyncTokenStatus::~SyncTokenStatus() {}
 
+std::unique_ptr<SyncSetupInProgressHandle>
+SyncService::GetSetupInProgressHandle() {
+  if (++outstanding_setup_in_progress_handles_ == 1)
+    SetSetupInProgress(true);
+
+  return std::unique_ptr<SyncSetupInProgressHandle>(
+      new SyncSetupInProgressHandle(
+          base::Bind(&SyncService::OnSetupInProgressHandleDestroyed,
+                     base::Unretained(this))));

[tommycli, 2016/06/09 17:46:38]

Will the SyncService ever get destroyed before the UI holding these handles? If
that can happen, we need to use a weak pointer instead of the base::Unretained
raw ptr.

[Nicolas Zea, 2016/06/09 23:02:01]

It shouldn't, but either way this seems brittle. I'd prefer using a weak ptr
here, which the profile sync service has access to (going along with Max's
comment about having this logic be in ProfileSyncService).

[tommycli, 2016/06/10 00:04:15]

Done.

 }
+
+void SyncService::OnSetupInProgressHandleDestroyed() {
+  if (--outstanding_setup_in_progress_handles_ == 0)
+    SetSetupInProgress(false);
+}
+
+}  // namespace sync_driver