[SyncFS] Make MetadataDatabase operations synchronous

chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer.cc

Index: chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer.cc
diff --git a/chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer.cc b/chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer.cc
index 50e048589da91107117070978a2a68df0c112523..5a620d017ce799fd9960f42a9665683c78c2e36c 100644
--- a/chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer.cc
+++ b/chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer.cc
@@ -370,7 +370,6 @@ void LocalToRemoteSyncer::HandleConflict(scoped_ptr<SyncTaskToken> token) {
       remote_details.title() == title.AsUTF8Unsafe() &&
       HasFileAsParent(remote_details,
                       remote_parent_folder_tracker_->file_id())) {
-
     MoveToBackground(
         base::Bind(&LocalToRemoteSyncer::UpdateTrackerForReusedFolder,
                    weak_ptr_factory_.GetWeakPtr(),
@@ -387,11 +386,9 @@ void LocalToRemoteSyncer::HandleConflict(scoped_ptr<SyncTaskToken> token) {
 void LocalToRemoteSyncer::UpdateTrackerForReusedFolder(
     const FileDetails& details,
     scoped_ptr<SyncTaskToken> token) {
-  metadata_database()->UpdateTracker(
-      remote_file_tracker_->tracker_id(), details,
-      base::Bind(&LocalToRemoteSyncer::SyncCompleted,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 base::Passed(&token)));
+  SyncStatusCode status = metadata_database()->UpdateTracker(
+      remote_file_tracker_->tracker_id(), details);
+  SyncCompleted(token.Pass(), status);
 }
 
 void LocalToRemoteSyncer::HandleExistingRemoteFile(
@@ -482,10 +479,9 @@ void LocalToRemoteSyncer::DidDeleteRemoteFile(
   // resolution, ignore the local deletion.
   if (status == SYNC_STATUS_OK ||
       error == google_apis::HTTP_NOT_FOUND) {
-    metadata_database()->UpdateByDeletedRemoteFile(
-        remote_file_tracker_->file_id(),
-        base::Bind(&LocalToRemoteSyncer::SyncCompleted,
-                   weak_ptr_factory_.GetWeakPtr(), base::Passed(&token)));
+    SyncStatusCode status = metadata_database()->UpdateByDeletedRemoteFile(
+        remote_file_tracker_->file_id());
+    SyncCompleted(token.Pass(), status);
     return;
   }
 
@@ -551,11 +547,10 @@ void LocalToRemoteSyncer::DidUploadExistingFile(
   }
 
   DCHECK(entry);
-  metadata_database()->UpdateByFileResource(
-      *entry,
-      base::Bind(&LocalToRemoteSyncer::DidUpdateDatabaseForUploadExistingFile,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 base::Passed(&token)));
+  status = metadata_database()->UpdateByFileResource(*entry);
+
+  // TODO(tzik): Expand this function.
+  DidUpdateDatabaseForUploadExistingFile(token.Pass(), status);
 }
 
 void LocalToRemoteSyncer::DidUpdateDatabaseForUploadExistingFile(
@@ -581,12 +576,9 @@ void LocalToRemoteSyncer::DidUpdateDatabaseForUploadExistingFile(
       details.title() == title.AsUTF8Unsafe() &&
       HasFileAsParent(details,
                       remote_parent_folder_tracker_->file_id())) {
-    metadata_database()->UpdateTracker(
-        remote_file_tracker_->tracker_id(),
-        file.details(),
-        base::Bind(&LocalToRemoteSyncer::SyncCompleted,
-                   weak_ptr_factory_.GetWeakPtr(),
-                   base::Passed(&token)));
+    SyncStatusCode status = metadata_database()->UpdateTracker(
+        remote_file_tracker_->tracker_id(), file.details());
+    SyncCompleted(token.Pass(), status);
     return;
   }
 
@@ -614,11 +606,9 @@ void LocalToRemoteSyncer::DidGetRemoteMetadata(
 
   if (error == google_apis::HTTP_NOT_FOUND) {
     retry_on_success_ = true;
-    metadata_database()->UpdateByDeletedRemoteFile(
-        file_id,
-        base::Bind(&LocalToRemoteSyncer::SyncCompleted,
-                   weak_ptr_factory_.GetWeakPtr(),
-                   base::Passed(&token)));
+    SyncStatusCode status =
+        metadata_database()->UpdateByDeletedRemoteFile(file_id);
+    SyncCompleted(token.Pass(), status);
     return;
   }
 
@@ -635,11 +625,8 @@ void LocalToRemoteSyncer::DidGetRemoteMetadata(
   }
 
   retry_on_success_ = true;
-  metadata_database()->UpdateByFileResource(
-      *entry,
-      base::Bind(&LocalToRemoteSyncer::SyncCompleted,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 base::Passed(&token)));
+  status = metadata_database()->UpdateByFileResource(*entry);
+  SyncCompleted(token.Pass(), status);
 }
 
 void LocalToRemoteSyncer::UploadNewFile(scoped_ptr<SyncTaskToken> token) {
@@ -679,11 +666,9 @@ void LocalToRemoteSyncer::DidUploadNewFile(
     return;
   }
 
-  metadata_database()->ReplaceActiveTrackerWithNewResource(
-      remote_parent_folder_tracker_->tracker_id(), *entry,
-      base::Bind(&LocalToRemoteSyncer::SyncCompleted,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 base::Passed(&token)));
+  status = metadata_database()->ReplaceActiveTrackerWithNewResource(
+      remote_parent_folder_tracker_->tracker_id(), *entry);
+  SyncCompleted(token.Pass(), status);
 }
 
 void LocalToRemoteSyncer::CreateRemoteFolder(
@@ -717,17 +702,14 @@ void LocalToRemoteSyncer::DidCreateRemoteFolder(
     return;
   }
 
+  status = SYNC_STATUS_FAILED;
   MetadataDatabase::ActivationStatus activation_status =
       metadata_database()->TryActivateTracker(
           remote_parent_folder_tracker_->tracker_id(),
-          file_id,
-          base::Bind(&LocalToRemoteSyncer::SyncCompleted,
-                     weak_ptr_factory_.GetWeakPtr(),
-                     base::Passed(token.Pass())));
+          file_id, &status);
   switch (activation_status) {
     case MetadataDatabase::ACTIVATION_PENDING:
-      // The task will be finalized by the callback passed to MetadataDatabase
-      // in this case.
+      SyncCompleted(token.Pass(), status);
       return;
     case MetadataDatabase::ACTIVATION_FAILED_ANOTHER_ACTIVE_TRACKER:
       // The activation failed due to another tracker that has another parent.