Sync: Support multiple setup UIs.

components/browser_sync/browser/profile_sync_service.h

Index: components/browser_sync/browser/profile_sync_service.h
diff --git a/components/browser_sync/browser/profile_sync_service.h b/components/browser_sync/browser/profile_sync_service.h
index 3fecc3197fa8b306fb396ec8b051385d7a41aae3..5d03bc4dc4c1f17dad9a2f727c5b5453d93e0427 100644
--- a/components/browser_sync/browser/profile_sync_service.h
+++ b/components/browser_sync/browser/profile_sync_service.h
@@ -165,14 +165,16 @@ class EncryptedData;
 //   that control the initial sync download:
 //
 //    * SetFirstSetupComplete()
-//    * SetSetupInProgress()
+//    * GetSetupInProgressHandle()
 //
 //   SetFirstSetupComplete() should be called once the user has finished setting
-//   up sync at least once on their account. SetSetupInProgress(true) should be
-//   called while the user is actively configuring their account, and then
-//   SetSetupInProgress(false) should be called when configuration is complete.
-//   Once both these conditions have been met, CanConfigureDataTypes() will
-//   return true and datatype configuration can begin.
+//   up sync at least once on their account. GetSetupInProgressHandle() should
+//   be called while the user is actively configuring their account. The handle
+//   should be deleted once configuration is complete.
+//
+//   Once first setup has completed and there are no outstanding
+//   setup-in-progress handles, CanConfigureDataTypes() will return true and
+//   datatype configuration can begin.
 class ProfileSyncService : public sync_driver::SyncService,
                            public sync_driver::SyncFrontend,
                            public sync_driver::SyncPrefObserver,
@@ -280,7 +282,6 @@ class ProfileSyncService : public sync_driver::SyncService,
                             syncer::ModelTypeSet chosen_types) override;
   void SetFirstSetupComplete() override;
   bool IsFirstSetupInProgress() const override;
-  void SetSetupInProgress(bool setup_in_progress) override;
   bool IsSetupInProgress() const override;
   bool ConfigurationDone() const override;
   const GoogleServiceAuthError& GetAuthError() const override;
@@ -594,6 +595,9 @@ class ProfileSyncService : public sync_driver::SyncService,
   void RefreshTypesForTest(syncer::ModelTypeSet types);
 
  protected:
+  // sync_driver::SyncService implementation
+  void SetSetupInProgress(bool setup_in_progress) override;
+
   // Helper to install and configure a data type manager.
   void ConfigureDataTypeManager();