Modify test case to support streaming operation in sandbox file system.

webkit/browser/fileapi/file_system_context.cc

Index: webkit/browser/fileapi/file_system_context.cc
diff --git a/webkit/browser/fileapi/file_system_context.cc b/webkit/browser/fileapi/file_system_context.cc
index cb62556fefe3cb855c4367b8f0147b1079b1085e..7de00a5638bf8cb09e894dd75ed94055d0714434 100644
--- a/webkit/browser/fileapi/file_system_context.cc
+++ b/webkit/browser/fileapi/file_system_context.cc
@@ -298,6 +298,14 @@ const UpdateObserverList* FileSystemContext::GetUpdateObservers(
   return NULL;
 }
 
+const ChangeObserverList* FileSystemContext::GetChangeObservers(
+    FileSystemType type) const {
+  FileSystemBackend* backend = GetFileSystemBackend(type);
+  if (backend->GetQuotaUtil())
+    return backend->GetQuotaUtil()->GetChangeObservers(type);
+  return NULL;
+}
+
 const AccessObserverList* FileSystemContext::GetAccessObservers(
     FileSystemType type) const {
   FileSystemBackend* backend = GetFileSystemBackend(type);