[mac] Use -[NSApp isActive] for checking if current app is active.

chrome/browser/mac/relauncher.mm

Index: chrome/browser/mac/relauncher.mm
diff --git a/chrome/browser/mac/relauncher.mm b/chrome/browser/mac/relauncher.mm
index bbb56fff51d22c9fff5eb2da45f398d004a5cb56..1ad1042256f030cbba8e0ccbb90517f0c825dcf3 100644
--- a/chrome/browser/mac/relauncher.mm
+++ b/chrome/browser/mac/relauncher.mm
@@ -100,7 +100,7 @@ bool RelaunchAppWithHelper(const std::string& helper,
 
   // If this application isn't in the foreground, the relaunched one shouldn't
   // be either.
-  if (![[NSRunningApplication currentApplication] isActive]) {
+  if (![NSApp isActive]) {
     relaunch_args.push_back(kRelauncherBackgroundArg);
   }