Revert of [ObjC ARC] Converts ios/chrome/browser/ui:ui to ARC.

ios/chrome/browser/ui/uikit_ui_util.mm

 // Copyright 2012 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/ui/uikit_ui_util.h"
 
 #import <Accelerate/Accelerate.h>
 #import <Foundation/Foundation.h>
 #import <QuartzCore/QuartzCore.h>
 #include <stddef.h>
 #include <stdint.h>
 #import <UIKit/UIKit.h>
 #include <cmath>
 
 #include "base/ios/ios_util.h"
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
+#include "base/mac/scoped_nsobject.h"
 #include "ios/chrome/browser/experimental_flags.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #include "ios/web/public/web_thread.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/gfx/ios/uikit_util.h"
 #include "ui/gfx/scoped_cg_context_save_gstate_mac.h"
 
-#if !defined(__has_feature) || !__has_feature(objc_arc)
-#error "This file requires ARC support."
-#endif
-
 namespace {
 
 // Linearly interpolate between |a| and |b| by fraction |f|. Satisfies
 // |Lerp(a,b,0) == a| and |Lerp(a,b,1) == b|.
 CGFloat Lerp(CGFloat a, CGFloat b, CGFloat fraction) {
   return a * (1.0f - fraction) + b * fraction;
 }
 
 // Gets the RGBA components from a UIColor in RBG or monochrome color space.
 void GetRGBA(UIColor* color, CGFloat* r, CGFloat* g, CGFloat* b, CGFloat* a) {
@@ skipping 508 matching lines @@
                                        NSDictionary* metrics,
                                        UIView* unused_parentView) {
   ApplyVisualConstraintsWithMetrics(constraints, subviewsDictionary, metrics);
 }
 
 void ApplyVisualConstraintsWithMetricsAndOptions(
     NSArray* constraints,
     NSDictionary* subviewsDictionary,
     NSDictionary* metrics,
     NSLayoutFormatOptions options) {
-  NSMutableArray* layoutConstraints =
-      [NSMutableArray arrayWithCapacity:constraints.count * 3];
+  base::scoped_nsobject<NSMutableArray> layoutConstraints(
+      [[NSMutableArray arrayWithCapacity:constraints.count * 3] retain]);
   for (NSString* constraint in constraints) {
     DCHECK([constraint isKindOfClass:[NSString class]]);
     [layoutConstraints addObjectsFromArray:
                            [NSLayoutConstraint
                                constraintsWithVisualFormat:constraint
                                                    options:options
                                                    metrics:metrics
                                                      views:subviewsDictionary]];
   }
   [NSLayoutConstraint activateConstraints:layoutConstraints];
@@ skipping 69 matching lines @@
   DCHECK(!gFirstResponder);
   [[UIApplication sharedApplication]
       sendAction:@selector(cr_markSelfCurrentFirstResponder)
               to:nil
             from:nil
         forEvent:nil];
   UIResponder* firstResponder = gFirstResponder;
   gFirstResponder = nil;
   return firstResponder;
 }