Added read-only file error test.

base/test/test_file_util.h

Index: base/test/test_file_util.h
diff --git a/base/test/test_file_util.h b/base/test/test_file_util.h
index ce0b30259371cd845ab90d45f592a395cb82b5da..9a4bb4a01b42ec7cf402a07db824a13bcfdae080 100644
--- a/base/test/test_file_util.h
+++ b/base/test/test_file_util.h
@@ -56,6 +56,18 @@ FilePath WStringAsFilePath(const std::wstring& path);
 bool MakeFileUnreadable(const FilePath& path) WARN_UNUSED_RESULT;
 bool MakeFileUnwritable(const FilePath& path) WARN_UNUSED_RESULT;
 
+// Gets a blob indicating the permission information for |path|.
+// |length| is the length of the blob.  Zero on failure.
+// Returns the blob pointer, or NULL on failure.
+void* GetPermissionInfo(const FilePath& path, size_t* length);
+
+// Restores the permission information for |path|, given the blob retrieved
+// using |GetPermissionInfo()|.
+// |info| is the pointer to the blob.
+// |length| is the length of the blob.
+// Either |info| or |length| may be NULL/0, in which case nothing happens.
+bool RestorePermissionInfo(const FilePath& path, void* info, size_t length);
+
 }  // namespace file_util
 
 #endif  // BASE_TEST_TEST_FILE_UTIL_H_