[SyncFS] Add NULL check to SyncFileSystemService::DidInitializeFileSystemForDump

chrome/browser/sync_file_system/sync_file_system_service.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/sync_file_system/sync_file_system_service.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/format_macros.h"
@@ skipping 487 matching lines @@
   DCHECK(!origin.is_empty());
 
   if (status != SYNC_STATUS_OK) {
     base::ListValue empty_result;
     callback.Run(&empty_result);
     return;
   }
 
   base::ListValue* files =
       GetRemoteService(origin)->DumpFiles(origin).release();
+  if (!files) {
+    callback.Run(new base::ListValue);
+    return;
+  }
+
   if (!files->GetSize()) {
     callback.Run(files);
     return;
   }
 
   base::Callback<void(base::DictionaryValue* file,
                       SyncStatusCode sync_status,
                       SyncFileStatus sync_file_status)> completion_callback =
       base::Bind(&DidGetFileSyncStatusForDump, base::Owned(files),
                  base::Owned(new size_t(0)), callback);
@@ skipping 217 matching lines @@
                              v2_remote_service_.get()));
     v2_remote_service_->AddServiceObserver(v2_remote_syncer.get());
     v2_remote_service_->AddFileStatusObserver(this);
     v2_remote_service_->SetRemoteChangeProcessor(local_service_.get());
     sync_runners_.push_back(v2_remote_syncer.release());
   }
   return v2_remote_service_.get();
 }
 
 }  // namespace sync_file_system