Add information about sync session and other useful data to about:sync.

chrome/browser/sync/sessions/status_controller.cc

Index: chrome/browser/sync/sessions/status_controller.cc
diff --git a/chrome/browser/sync/sessions/status_controller.cc b/chrome/browser/sync/sessions/status_controller.cc
index c938fe56f7e4de607a7992c590e80332190f4964..8c3b780a865be2ee2da422e763b0c8b2b9e4c6e3 100644
--- a/chrome/browser/sync/sessions/status_controller.cc
+++ b/chrome/browser/sync/sessions/status_controller.cc
@@ -110,6 +110,11 @@ void StatusController::set_syncing(bool syncing) {
     shared_.syncer_status.mutate()->syncing = syncing;
 }
 
+void StatusController::set_throttled() {
+  if (shared_.syncer_status.value().throttled != true)
+    shared_.syncer_status.mutate()->throttled = true;
+}
+
 void StatusController::set_num_successful_bookmark_commits(int value) {
   if (shared_.syncer_status.value().num_successful_bookmark_commits != value)
     shared_.syncer_status.mutate()->num_successful_bookmark_commits = value;