Cleanup: Remove VersionUpdater::RelaunchBrowser interface method.

chrome/browser/lifetime/application_lifetime.h

Index: chrome/browser/lifetime/application_lifetime.h
diff --git a/chrome/browser/lifetime/application_lifetime.h b/chrome/browser/lifetime/application_lifetime.h
index 051d38e14fa4b22976f60422c8969543409d2bcb..55bf2f8104f39d66f0d6dc9b169bd4ab20e3d4a2 100644
--- a/chrome/browser/lifetime/application_lifetime.h
+++ b/chrome/browser/lifetime/application_lifetime.h
@@ -26,6 +26,11 @@ void AttemptUserExit();
 // manager re-launch the browser with restore last session flag.
 void AttemptRestart();
 
+// Starts a user initiated relaunch process. On platforms other than
+// chromeos, this is equivalent to AttemptRestart. On ChromeOS, this relaunches
+// the entire OS, instead of just relaunching the browser.
+void AttemptRelaunch();
+
 // Attempt to exit by closing all browsers.  This is equivalent to
 // CloseAllBrowsers() on platforms where the application exits
 // when no more windows are remaining. On other platforms (the Mac),