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..a1be9cf1561842a7a063197688c6c8229e7e9856
--- /dev/null
+++ b/chrome/installer/util/delete_old_versions.h
@@ -0,0 +1,26 @@
+// 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_
+
+namespace base {
+class FilePath;
+}
+
+class CallbackWorkItem;
+
+// 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);
+
+// Wrapper around DeleteOldVersions() which can be used to instantiate a
+// CallbackWorkItem.
+bool DeleteOldVersionsCallback(const base::FilePath& install_dir,

[grt (UTC plus 2), 2016/02/24 20:06:17]

how about replacing this with AddDeleteOldVersionsWorkItem(const
base::FilePath&, WorkItemList*)?

[fdoray, 2016/02/25 18:26:48]

Done. InstallerState instead of base::FilePath because I now call
installer_state->UpdateStage() inside the callback. 

+                               const CallbackWorkItem& work_item);
+
+#endif  // CHROME_INSTALLER_UTIL_DELETE_OLD_VERSIONS_H_