[SyncFS] Retry initialization of MetadataDatabase on failure of loading ServiceMetadata

chrome/browser/sync_file_system/drive_backend/drive_backend_util.cc

 // Copyright 2013 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/drive_backend/drive_backend_util.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_vector.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
@@ skipping 151 matching lines @@
 
   if (out)
     *out = str.substr(prefix.size());
   return true;
 }
 
 scoped_ptr<ServiceMetadata> InitializeServiceMetadata(LevelDBWrapper* db) {
   base::ThreadRestrictions::AssertIOAllowed();
   DCHECK(db);
 
+  scoped_ptr<ServiceMetadata> service_metadata;
+
   std::string value;
   leveldb::Status status = db->Get(kServiceMetadataKey, &value);
-
-  scoped_ptr<ServiceMetadata> service_metadata(new ServiceMetadata);
-  if (!status.ok() || !service_metadata->ParseFromString(value))
+  if (status.ok()) {
+    service_metadata.reset(new ServiceMetadata);
+    if (!service_metadata->ParseFromString(value))
+      service_metadata.reset();
+  } else if (status.IsNotFound()) {
+    service_metadata.reset(new ServiceMetadata);
     service_metadata->set_next_tracker_id(1);
+  }
 
   return service_metadata.Pass();
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system