DriveFileSyncService listens to OnAuthenticated event to recover from unavailable state

chrome/browser/sync_file_system/drive_file_sync_service.cc

Index: chrome/browser/sync_file_system/drive_file_sync_service.cc
diff --git a/chrome/browser/sync_file_system/drive_file_sync_service.cc b/chrome/browser/sync_file_system/drive_file_sync_service.cc
index 1ab7c8e6823a477dad3e6cf3bae1c89d11ad724a..d7a1d34b3b2e3a99adf09bb681107a7a20c2ab77 100644
--- a/chrome/browser/sync_file_system/drive_file_sync_service.cc
+++ b/chrome/browser/sync_file_system/drive_file_sync_service.cc
@@ -139,6 +139,7 @@ DriveFileSyncService::DriveFileSyncService(Profile* profile)
   token_.reset(new TaskToken(AsWeakPtr()));
 
   sync_client_.reset(new DriveFileSyncClient(profile));
+  sync_client_->AddObserver(this);
 
   metadata_store_.reset(new DriveMetadataStore(
       profile->GetPath(),
@@ -155,6 +156,7 @@ DriveFileSyncService::~DriveFileSyncService() {
   // Invalidate WeakPtr instances here explicitly to notify TaskToken that we
   // can safely discard the token.
   weak_factory_.InvalidateWeakPtrs();
+  sync_client_->RemoveObserver(this);
   token_.reset();
 }
 
@@ -372,6 +374,12 @@ void DriveFileSyncService::ApplyLocalChange(
                       callback, fileapi::SYNC_STATUS_FAILED);
 }
 
+void DriveFileSyncService::OnAuthenticated() {
+  FOR_EACH_OBSERVER(
+        Observer, observers_,
+        OnRemoteServiceStateUpdated(REMOTE_SERVICE_OK, "Authenticated"));
+}
+
 // Called by CreateForTesting.
 DriveFileSyncService::DriveFileSyncService(
     scoped_ptr<DriveFileSyncClient> sync_client,