[ObjC ARC] Converts ios/chrome/test/earl_grey:ios_chrome_multitasking_egtests to ARC.

ios/chrome/app/multitasking_test_application_delegate.mm

Index: ios/chrome/app/multitasking_test_application_delegate.mm
diff --git a/ios/chrome/app/multitasking_test_application_delegate.mm b/ios/chrome/app/multitasking_test_application_delegate.mm
index f5a3a8ebb7588f58846e49f93a7b91e4cf5593a9..7fddf09b70a85171403301eceec0d1bb336309f8 100644
--- a/ios/chrome/app/multitasking_test_application_delegate.mm
+++ b/ios/chrome/app/multitasking_test_application_delegate.mm
@@ -36,9 +36,9 @@ - (BOOL)application:(UIApplication*)application
     didFinishLaunchingWithOptions:(NSDictionary*)launchOptions {
   // Configure application window size for multitasking tests.
   CGSize newWindowSize = [self windowSize];
-  self.window = [[[ChromeOverlayWindow alloc]
-      initWithFrame:CGRectMake(0, 0, newWindowSize.width, newWindowSize.height)]
-      autorelease];
+  self.window = [[ChromeOverlayWindow alloc]
+      initWithFrame:CGRectMake(0, 0, newWindowSize.width,
+                               newWindowSize.height)];
 
   BOOL inBackground =
       [application applicationState] == UIApplicationStateBackground;