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 d58b7429f08aae41419ebecf1c0148515026d520..617479dfbe1701114acfbce7cb5d34c56edb5fda 100644
--- a/chrome/browser/sync/profile_sync_service.cc
+++ b/chrome/browser/sync/profile_sync_service.cc
@@ -953,13 +953,16 @@ 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;
   }
 }