Add Transient FileSystem which goes away after its snapsot file is gone

webkit/fileapi/file_system_types.h

Index: webkit/fileapi/file_system_types.h
diff --git a/webkit/fileapi/file_system_types.h b/webkit/fileapi/file_system_types.h
index 073f67e5a384d394890ab8138fd2e381fe55ce22..49d2b988fcacd8bdc466894da448dd045702348f 100644
--- a/webkit/fileapi/file_system_types.h
+++ b/webkit/fileapi/file_system_types.h
@@ -86,6 +86,13 @@ enum FileSystemType {
   // the handlers of kFileSystemTypeExternal.
   kFileSystemTypeNativeForPlatformApp,
 
+  // Indicates an isolated filesystem which is supposed to contain one
+  // temporary which is supposed to go away when the last reference of
+  // its snapshot is dropped.
+  // This type is useful for creating a blob reference for a temporary
+  // file which must go away when the blob's last reference is dropped.
+  kFileSystemTypeForTransientFile,
+
   // --------------------------------------------------------------------
   // Marks the end of internal type enum. (This is not the actual fs type)
   // New internal filesystem types must be added above this line.