Expose local sync mode status in the chrome://sync-internals page.

components/sync/engine_impl/all_status.cc

Index: components/sync/engine_impl/all_status.cc
diff --git a/components/sync/engine_impl/all_status.cc b/components/sync/engine_impl/all_status.cc
index e311e019fccc8d0fc67f21a4d144aa27eb07d726..177c930795021b263fb3e4a2056bb3babdd0bd20 100644
--- a/components/sync/engine_impl/all_status.cc
+++ b/components/sync/engine_impl/all_status.cc
@@ -185,6 +185,11 @@ void AllStatus::IncrementNudgeCounter(NudgeSource source) {
   NOTREACHED();
 }
 
+void AllStatus::SetLocalBackendFolder(const std::string& folder) {
+  ScopedStatusLock lock(this);
+  status_.local_sync_folder = folder;
+}
+
 ScopedStatusLock::ScopedStatusLock(AllStatus* allstatus)
     : allstatus_(allstatus) {
   allstatus->mutex_.Acquire();