drive: Use ResourceMetadataStorage from FileCache

chrome/browser/chromeos/drive/resource_metadata_storage.h

Index: chrome/browser/chromeos/drive/resource_metadata_storage.h
diff --git a/chrome/browser/chromeos/drive/resource_metadata_storage.h b/chrome/browser/chromeos/drive/resource_metadata_storage.h
index d5ae085b95ef73027f31fe34605d0da9f6811cd1..df42af7e52b06085fa7adbd21e5c74f2a376a24e 100644
--- a/chrome/browser/chromeos/drive/resource_metadata_storage.h
+++ b/chrome/browser/chromeos/drive/resource_metadata_storage.h
@@ -103,6 +103,10 @@ class ResourceMetadataStorage {
 
   const base::FilePath& directory_path() const { return directory_path_; }
 
+  // Returns true if the DB used by this storage was opened, not created, during
+  // Initialize().
+  bool opened_existing_db() const { return opened_existing_db_; }
+
   // Destroys this object.
   void Destroy();
 
@@ -173,6 +177,8 @@ class ResourceMetadataStorage {
   // Path to the directory where the data is stored.
   base::FilePath directory_path_;
 
+  bool opened_existing_db_;
+
   // Entries stored in this storage.
   scoped_ptr<leveldb::DB> resource_map_;