[ObjC ARC] Converts ios/chrome/browser/ui/alert_coordinator:eg_tests to ARC.

ios/chrome/browser/ui/alert_coordinator/alert_coordinator_egtest.mm

Index: ios/chrome/browser/ui/alert_coordinator/alert_coordinator_egtest.mm
diff --git a/ios/chrome/browser/ui/alert_coordinator/alert_coordinator_egtest.mm b/ios/chrome/browser/ui/alert_coordinator/alert_coordinator_egtest.mm
index 02a83608e52d11eae427de1eb7f4da380870edcc..f8812349ff6c8963590c54957a5be4449af4cfb6 100644
--- a/ios/chrome/browser/ui/alert_coordinator/alert_coordinator_egtest.mm
+++ b/ios/chrome/browser/ui/alert_coordinator/alert_coordinator_egtest.mm
@@ -6,13 +6,16 @@
 #import <UIKit/UIKit.h>
 #import <XCTest/XCTest.h>
 
-#import "base/mac/scoped_nsobject.h"
 #include "components/strings/grit/components_strings.h"
 #import "ios/chrome/browser/ui/alert_coordinator/alert_coordinator.h"
 #import "ios/chrome/test/earl_grey/chrome_matchers.h"
 #import "ios/chrome/test/earl_grey/chrome_test_case.h"
 #import "ios/testing/earl_grey/disabled_test_macros.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 NSString* kTitle = @"Foo Title";
 }  // namespace
@@ -39,16 +42,16 @@ NSString* kTitle = @"Foo Title";
   UIViewController* topViewController =
       [[[UIApplication sharedApplication] keyWindow] rootViewController];
 
-  base::scoped_nsobject<AlertCoordinator> alertCoordinator(
+  AlertCoordinator* alertCoordinator =
       [[AlertCoordinator alloc] initWithBaseViewController:topViewController
                                                      title:kTitle
-                                                   message:nil]);
+                                                   message:nil];
 
   [alertCoordinator start];
 
   GREYAssertTrue([self isPresentingAlert], @"An alert should be presented");
 
-  alertCoordinator.reset();
+  alertCoordinator = nil;

[gambard, 2017/02/08 16:08:29]

The alert coordinator needs to be dealloc here, before the next instruction. Is
this guaranteed with ARC?

[stkhapugin, 2017/02/08 17:39:29]

Generally, it is incorrect to assume exact object lifetimes both under ARC and
without ARC for Objective-C reference counted objects. 

[gambard, 2017/02/09 09:06:45]

Acknowledged.

 
   GREYAssertFalse([self isPresentingAlert], @"The alert should be removed");
 }
@@ -64,10 +67,10 @@ NSString* kTitle = @"Foo Title";
   UIViewController* topViewController =
       [[[UIApplication sharedApplication] keyWindow] rootViewController];
 
-  base::scoped_nsobject<AlertCoordinator> alertCoordinator(
+  AlertCoordinator* alertCoordinator =
       [[AlertCoordinator alloc] initWithBaseViewController:topViewController
                                                      title:kTitle
-                                                   message:nil]);
+                                                   message:nil];
 
   __block BOOL blockCalled = NO;