Delete old files after an update.

chrome/installer/util/delete_old_versions.h

Index: chrome/installer/util/delete_old_versions.h
diff --git a/chrome/installer/util/delete_old_versions.h b/chrome/installer/util/delete_old_versions.h
new file mode 100644
index 0000000000000000000000000000000000000000..8bc97658b46daf17742d296833177589a7d2b289
--- /dev/null
+++ b/chrome/installer/util/delete_old_versions.h
@@ -0,0 +1,19 @@
+// Copyright (c) 2016 The Chromium Authors. All rights reserved.

[grt (UTC plus 2), 2016/02/10 20:02:04]

nit: no "(c)" in new file headers
(http://www.chromium.org/developers/coding-style#TOC-File-headers)

[fdoray, 2016/02/18 17:59:20]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_INSTALLER_UTIL_DELETE_OLD_VERSIONS_H_
+#define CHROME_INSTALLER_UTIL_DELETE_OLD_VERSIONS_H_
+
+namespace base {
+class FilePath;
+}
+
+// Deletes files that belong to old versions of Chrome from |install_dir|.
+// chrome.exe, new_chrome.exe and their associated version directories are never
+// deleted. Also, no file is deleted for a given version if a .exe or .dll file
+// for that version is in use. Returns true if all old files were deleted
+// successfully.
+bool DeleteOldVersions(const base::FilePath& install_dir);
+
+#endif  // CHROME_INSTALLER_UTIL_DELETE_OLD_VERSIONS_H_