[ObjC ARC] Converts ios/chrome/browser/passwords:passwords_internal to ARC.

ios/chrome/browser/passwords/passwords_ui_delegate_impl.mm

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/chrome/browser/passwords/passwords_ui_delegate_impl.h"
 
 #import "ios/chrome/browser/passwords/password_generation_prompt_view.h"
 #import "ios/chrome/browser/passwords/password_generation_prompt_view_controller.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @implementation PasswordsUiDelegateImpl
 
 #pragma mark -
 #pragma mark PasswordsUiDelegate
 
 - (void)showGenerationAlertWithPassword:(NSString*)password
                       andPromptDelegate:
                           (id<PasswordGenerationPromptDelegate>)delegate {
   UIViewController* topViewController =
       [[[UIApplication sharedApplication] keyWindow] rootViewController];
 
   // Look for the top-most presented ViewController.
   for (UIViewController* controller = topViewController.presentedViewController;
        controller && ![controller isBeingDismissed];
        controller = controller.presentedViewController) {
     // Return if a PasswordGenerationPromptViewController is already presented.
     if ([controller
             isKindOfClass:[PasswordGenerationPromptViewController class]])
       return;
 
     topViewController = controller;
   }
 
   PasswordGenerationPromptDialog* contentView =
-      [[[PasswordGenerationPromptDialog alloc]
+      [[PasswordGenerationPromptDialog alloc]
           initWithDelegate:delegate
-            viewController:topViewController] autorelease];
+            viewController:topViewController];
 
   UIViewController* viewController =
-      [[[PasswordGenerationPromptViewController alloc]
+      [[PasswordGenerationPromptViewController alloc]
           initWithPassword:password
                contentView:contentView
-            viewController:topViewController] autorelease];
+            viewController:topViewController];
 
   [topViewController presentViewController:viewController
                                   animated:YES
                                 completion:nil];
 }
 
 - (void)hideGenerationAlert {
   UIViewController* rootViewController =
       [[[UIApplication sharedApplication] keyWindow] rootViewController];
 
   // Check every presented ViewController for a password generation prompt.
   for (UIViewController* controller = rootViewController;
        controller && ![controller isBeingDismissed];
        controller = controller.presentedViewController) {
     if ([controller.presentedViewController
             isKindOfClass:[PasswordGenerationPromptViewController class]]) {
       // Dismiss the password prompt.
       [controller dismissViewControllerAnimated:NO completion:nil];
       return;
     }
   }
 }
 
 @end