Sync: Support multiple setup UIs.

chrome/browser/ui/webui/options/sync_setup_handler.h

Index: chrome/browser/ui/webui/options/sync_setup_handler.h
diff --git a/chrome/browser/ui/webui/options/sync_setup_handler.h b/chrome/browser/ui/webui/options/sync_setup_handler.h
index 2ca7278e8373db9a14a9e452c92566c0fb4957b9..8aafcee48fcc521a8974bb9f41819a86af6b7e31 100644
--- a/chrome/browser/ui/webui/options/sync_setup_handler.h
+++ b/chrome/browser/ui/webui/options/sync_setup_handler.h
@@ -27,6 +27,10 @@ namespace signin_metrics {
 enum class AccessPoint;
 }
 
+namespace sync_driver {
+class SyncSetupInProgressHandle;
+}
+
 class SyncSetupHandler : public options::OptionsPageUIHandler,
                          public SyncStartupTracker::Observer,
                          public LoginUIService::LoginUI {
@@ -153,6 +157,9 @@ class SyncSetupHandler : public options::OptionsPageUIHandler,
   // Helper object used to wait for the sync backend to startup.
   std::unique_ptr<SyncStartupTracker> sync_startup_tracker_;
 
+  // Handle preventing Sync from running until configuration is complete.

[Lei Zhang, 2016/06/13 20:38:51]

Ditto ditto

[tommycli, 2016/06/13 21:08:35]

Done.

+  std::unique_ptr<sync_driver::SyncSetupInProgressHandle> setup_handle_;
+
   // Set to true whenever the sync configure UI is visible. This is used to tell
   // what stage of the setup wizard the user was in and to update the UMA
   // histograms in the case that the user cancels out.