Added implementation of SyncEventObserver to route events to Javascript Extension.

chrome/browser/extensions/event_names.cc

Index: chrome/browser/extensions/event_names.cc
diff --git a/chrome/browser/extensions/event_names.cc b/chrome/browser/extensions/event_names.cc
index e71b887192ff32202ff11a32d2acc7616b75f20d..a342530fc6392f847aea02a08eebc1801c214b29 100644
--- a/chrome/browser/extensions/event_names.cc
+++ b/chrome/browser/extensions/event_names.cc
@@ -78,6 +78,9 @@ const char kOnStorageRemoved[] = "experimental.systemInfo.storage.onRemoved";
 
 const char kOnSystemIndicatorClicked[] = "systemIndicator.onClicked";
 
+const char kOnSyncStateChanged[] = "syncFileSystem.onSyncStateChanged";
+const char kOnFileSynced[] = "syncFileSystem.onFileSynced";
+
 }  // namespace event_names
 
 }  // namespace extensions