chromeos: Add DriveFileSystem::Pin/Unpin

chrome/browser/chromeos/drive/mock_drive_file_system.h

Index: chrome/browser/chromeos/drive/mock_drive_file_system.h
diff --git a/chrome/browser/chromeos/drive/mock_drive_file_system.h b/chrome/browser/chromeos/drive/mock_drive_file_system.h
index 9b0e81fd4f3ae5df1ebb15bfbad032b0bf88472c..0cceaa0fcf0719e6a83de77bf26fdebcf5bb8163 100644
--- a/chrome/browser/chromeos/drive/mock_drive_file_system.h
+++ b/chrome/browser/chromeos/drive/mock_drive_file_system.h
@@ -66,6 +66,10 @@ class MockDriveFileSystem : public DriveFileSystemInterface {
                void(const base::FilePath& file_path,
                     bool is_exclusive,
                     const FileOperationCallback& callback));
+  MOCK_METHOD2(Pin, void(const base::FilePath& file_path,
+                         const FileOperationCallback& callback));
+  MOCK_METHOD2(Unpin, void(const base::FilePath& file_path,
+                           const FileOperationCallback& callback));
   MOCK_METHOD2(GetFileByPath,
                void(const base::FilePath& file_path,
                     const GetFileCallback& callback));