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