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..37c351c2a197c18f46774bdc0b24e66078cf6fe4
--- /dev/null
+++ b/chrome/installer/util/delete_old_versions.h
@@ -0,0 +1,25 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// 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_
+
+class WorkItem;
+class WorkItemList;
+
+namespace installer {
+
+class InstallerState;
+
+// Adds to |work_item_list| a WorkItem which deletes files that belong to old
+// versions of Chrome. 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. |installer_state| has to

[grt (UTC plus 2), 2016/02/25 19:25:40]

nit: "has to be" -> "must be"

[fdoray, 2016/02/26 17:00:05]

Done.

+// be alive when |work_item_list| is executed. Returns the added WorkItem.
+WorkItem* AddDeleteOldVersionsWorkItem(const InstallerState& installer_state,
+                                       WorkItemList* work_item_list);
+
+}  // namespace installer
+
+#endif  // CHROME_INSTALLER_UTIL_DELETE_OLD_VERSIONS_H_