Add RegisterMountPointProvider and TestMountPointProvider for testing

webkit/fileapi/file_system_mount_point_provider.h

Index: webkit/fileapi/file_system_mount_point_provider.h
diff --git a/webkit/fileapi/file_system_mount_point_provider.h b/webkit/fileapi/file_system_mount_point_provider.h
index ebce1de6bb963739169ff47bd681524cd117ddd5..af3ba14df47eada1182987e1127a19fab6ebba10 100644
--- a/webkit/fileapi/file_system_mount_point_provider.h
+++ b/webkit/fileapi/file_system_mount_point_provider.h
@@ -24,6 +24,7 @@ namespace fileapi {
 
 class FileSystemContext;
 class FileSystemFileUtil;
+class FileSystemQuotaUtil;
 class FileSystemOperationInterface;
 class RemoteFileSystemProxyInterface;
 
@@ -99,6 +100,10 @@ class FileSystemMountPointProvider {
     const GURL& url,
     int64 offset,
     FileSystemContext* context) const = 0;
+
+  // Returns the specialized FileSystemQuotaUtil for this mount point.
+  // This could return NULL if this mount point does not support quota.
+  virtual FileSystemQuotaUtil* GetQuotaUtil() { return NULL; }
 };
 
 // An interface to control external file system access permissions.