Files.app: Add a drive sync error event to the fileBrowserPrivate API.

chrome/browser/chromeos/drive/file_system.cc

Index: chrome/browser/chromeos/drive/file_system.cc
diff --git a/chrome/browser/chromeos/drive/file_system.cc b/chrome/browser/chromeos/drive/file_system.cc
index bfa7208830e619d00262a700345a051a516a3653..5b346edda9a5f1d46012977947a0a1e18a0cbc31 100644
--- a/chrome/browser/chromeos/drive/file_system.cc
+++ b/chrome/browser/chromeos/drive/file_system.cc
@@ -819,6 +819,12 @@ void FileSystem::OnEntryUpdatedByOperation(const std::string& local_id) {
   sync_client_->AddUpdateTask(local_id);
 }
 
+void FileSystem::OnDriveSyncError(file_system::DriveSyncErrorType type) {
+  FOR_EACH_OBSERVER(FileSystemObserver,
+                    observers_,
+                    OnDriveSyncError(type));
+}
+
 void FileSystem::OnDirectoryChanged(const base::FilePath& directory_path) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));