Add GetChangelist operation for Drive V2.

chrome/browser/chromeos/gdata/mock_gdata_documents_service.h

Index: chrome/browser/chromeos/gdata/mock_gdata_documents_service.h
diff --git a/chrome/browser/chromeos/gdata/mock_gdata_documents_service.h b/chrome/browser/chromeos/gdata/mock_gdata_documents_service.h
index b89ff176987879092eb0c7796023d00e85fea623..cd25acab0f673ffc3050c82c171f3b0c4f22a04e 100644
--- a/chrome/browser/chromeos/gdata/mock_gdata_documents_service.h
+++ b/chrome/browser/chromeos/gdata/mock_gdata_documents_service.h
@@ -34,6 +34,9 @@ class MockDocumentsService : public DocumentsServiceInterface {
                                   const std::string& search_string,
                                   const std::string& directory_resource_id,
                                   const GetDataCallback& callback));
+  MOCK_METHOD3(GetChangelist, void(const GURL& feed_url,
+                                   int64 start_changestamp,
+                                   const GetDataCallback& callback));
   MOCK_METHOD2(GetDocumentEntry, void(const std::string& resource_id,
                                       const GetDataCallback& callback));
   MOCK_METHOD1(GetAccountMetadata, void(const GetDataCallback& callback));