Support --delete-old-versions in setup.exe.

chrome/installer/setup/install.h

Index: chrome/installer/setup/install.h
diff --git a/chrome/installer/setup/install.h b/chrome/installer/setup/install.h
index 3671c6b6bdedb1719e5a29bb4458d716db8b7233..48343311cdeaed4c0f6e77e4befd3d379d48c4be 100644
--- a/chrome/installer/setup/install.h
+++ b/chrome/installer/setup/install.h
@@ -129,6 +129,9 @@ InstallStatus InstallOrUpdateProduct(
     const installer::MasterPreferences& prefs,
     const base::Version& new_version);
 
+// Launches a process that deletes files that belong to old versions of Chrome.
+void LaunchDeleteOldVersionsProcess(const InstallerState& installer_state);
+
 // Performs installation-related tasks following an OS upgrade.
 // |chrome| The installed product (must be a browser).
 // |installed_version| the current version of this install.