Sync: Support multiple setup UIs.

components/browser_sync/browser/profile_sync_service.cc

 // Copyright (c) 2012 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/browser_sync/browser/profile_sync_service.h"
 
 #include <stddef.h>
 #include <cstddef>
 #include <map>
 #include <utility>
@@ skipping 1512 matching lines @@
 }
 
 bool ProfileSyncService::CanConfigureDataTypes() const {
   return IsFirstSetupComplete() && !IsSetupInProgress();
 }
 
 bool ProfileSyncService::IsFirstSetupInProgress() const {
   return !IsFirstSetupComplete() && startup_controller_->IsSetupInProgress();
 }
 
-void ProfileSyncService::SetSetupInProgress(bool setup_in_progress) {
-  // This method is a no-op if |setup_in_progress_| remains unchanged.
-  if (startup_controller_->IsSetupInProgress() == setup_in_progress)
-    return;
+std::unique_ptr<sync_driver::SyncSetupInProgressHandle>
+ProfileSyncService::GetSetupInProgressHandle() {
+  if (++outstanding_setup_in_progress_handles_ == 1 &&
+      !startup_controller_->IsSetupInProgress()) {

[maxbogue, 2016/06/10 17:28:46]

You could probably DCHECK the !IsSetupInProgress part, no? Would be bad if the
count was 0 and that was true.

[tommycli, 2016/06/10 18:58:21]

Done. You're right that would really surprise me.

+    startup_controller_->SetSetupInProgress(true);
+    NotifyObservers();
+  }
 
-  startup_controller_->SetSetupInProgress(setup_in_progress);
-  if (!setup_in_progress && IsBackendInitialized())
-    ReconfigureDatatypeManager();
-  NotifyObservers();
+  return std::unique_ptr<sync_driver::SyncSetupInProgressHandle>(
+      new sync_driver::SyncSetupInProgressHandle(
+          base::Bind(&ProfileSyncService::OnSetupInProgressHandleDestroyed,
+                     weak_factory_.GetWeakPtr())));
 }
 
 bool ProfileSyncService::IsSyncAllowed() const {
   return IsSyncAllowedByFlag() && !IsManaged() && IsSyncAllowedByPlatform();
 }
 
 bool ProfileSyncService::IsSyncActive() const {
   return backend_initialized_ && data_type_manager_ &&
          data_type_manager_->state() != DataTypeManager::STOPPED;
 }
@@ skipping 985 matching lines @@
 }
 
 std::string ProfileSyncService::unrecoverable_error_message() const {
   return unrecoverable_error_message_;
 }
 
 tracked_objects::Location ProfileSyncService::unrecoverable_error_location()
     const {
   return unrecoverable_error_location_;
 }
+
+void ProfileSyncService::OnSetupInProgressHandleDestroyed() {
+  // Don't re-start Sync until all outstanding handles are destroyed.
+  if (--outstanding_setup_in_progress_handles_ != 0)
+    return;
+
+  if (!startup_controller_->IsSetupInProgress())

[maxbogue, 2016/06/10 17:28:46]

Same as above, would it make sense to DCHECK instead?

[tommycli, 2016/06/10 18:58:20]

Done.

+    return;
+
+  startup_controller_->SetSetupInProgress(false);
+  if (IsBackendInitialized())
+    ReconfigureDatatypeManager();
+  NotifyObservers();
+}