Set root resource ID upon full feed update.

chrome/browser/chromeos/drive/drive_feed_processor.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 <utility>
 
 #include "base/metrics/histogram.h"
 #include "chrome/browser/chromeos/drive/document_entry_conversion.h"
 #include "chrome/browser/chromeos/drive/drive_feed_processor.h"
 #include "chrome/browser/chromeos/drive/drive_files.h"
@@ skipping 74 matching lines @@
   DCHECK(changed_dirs);
 
   if (!is_delta_feed) {  // Full update.
     resource_metadata_->root()->RemoveChildren();
     changed_dirs->insert(resource_metadata_->root()->GetFilePath());
   }
   resource_metadata_->set_largest_changestamp(feed_changestamp);
 
   scoped_ptr<DriveResourceMetadata> orphaned_resources(
       new DriveResourceMetadata);
+  // This may look weird, but the root has to have some resource ID,
+  // otherwise cleaning up the resource metadata fails.
+  orphaned_resources->SetRootResourceId("orphan");
 
   // TODO(achuith): Get rid of this conversion of DriveEntryProtoMap to
   // ResourceMap.
   ResourceMap resource_map;
   for (DriveEntryProtoMap::const_iterator it = entry_proto_map.begin();
       it != entry_proto_map.end(); ++it) {
     scoped_ptr<DriveEntry> entry =
         resource_metadata_->CreateDriveEntryFromProto(it->second);
     resource_map.insert(std::make_pair(it->first, entry.release()));
   }
@@ skipping 176 matching lines @@
       std::pair<DriveEntryProtoMap::iterator, bool> ret = entry_proto_map->
           insert(std::make_pair(entry_proto.resource_id(), entry_proto));
       DCHECK(ret.second);
       if (!ret.second)
         LOG(WARNING) << "Found duplicate file " << entry_proto.base_name();
     }
   }
 }
 
 }  // namespace drive