sync: Track validity of about:sync fields

chrome/browser/sync/profile_sync_service.cc

Index: chrome/browser/sync/profile_sync_service.cc
diff --git a/chrome/browser/sync/profile_sync_service.cc b/chrome/browser/sync/profile_sync_service.cc
index fad95dc46e6f741329a82cd834a80622b9a1df9a..7fa28b89d5b21eead6ff2fe2cc757b6a56e3e707 100644
--- a/chrome/browser/sync/profile_sync_service.cc
+++ b/chrome/browser/sync/profile_sync_service.cc
@@ -970,13 +970,16 @@ std::string ProfileSyncService::QuerySyncStatusSummary() {
   }
 }
 
-SyncBackendHost::Status ProfileSyncService::QueryDetailedSyncStatus() {
+bool ProfileSyncService::QueryDetailedSyncStatus(
+    SyncBackendHost::Status* result) {
   if (backend_.get() && backend_initialized_) {
-    return backend_->GetDetailedStatus();
+    *result = backend_->GetDetailedStatus();
+    return true;
   } else {
     SyncBackendHost::Status status;
     status.sync_protocol_error = last_actionable_error_;
-    return status;
+    *result = status;
+    return false;
   }
 }