Upstreaming browser/ui/uikit_ui_util from iOS.

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>
 #import <UIKit/UIKit.h>
@@ skipping 439 matching lines @@
   [parentView addConstraint:[NSLayoutConstraint
                                 constraintWithItem:subview
                                          attribute:NSLayoutAttributeCenterX
                                          relatedBy:NSLayoutRelationEqual
                                             toItem:parentView
                                          attribute:NSLayoutAttributeCenterX
                                         multiplier:1
                                           constant:0]];
 }
 
+void AddSameCenterXConstraint(UIView *parentView, UIView *subview1,
+                              UIView *subview2) {
+  DCHECK_EQ(parentView, [subview1 superview]);
+  DCHECK_EQ(parentView, [subview2 superview]);
+  DCHECK_NE(subview1, subview2);
+  [parentView addConstraint:[NSLayoutConstraint
+                                constraintWithItem:subview1
+                                         attribute:NSLayoutAttributeCenterX
+                                         relatedBy:NSLayoutRelationEqual
+                                            toItem:subview2
+                                         attribute:NSLayoutAttributeCenterX
+                                        multiplier:1
+                                          constant:0]];
+}
+
 void AddSameCenterYConstraint(UIView* parentView, UIView* subview) {
   DCHECK_EQ(parentView, [subview superview]);
   [parentView addConstraint:[NSLayoutConstraint
                                 constraintWithItem:subview
                                          attribute:NSLayoutAttributeCenterY
                                          relatedBy:NSLayoutRelationEqual
                                             toItem:parentView
                                          attribute:NSLayoutAttributeCenterY
                                         multiplier:1
                                           constant:0]];
@@ skipping 22 matching lines @@
     return IsCompactTabletSizeClass(
         [rootController.traitCollection horizontalSizeClass]);
   } else {
     return IsCompactTabletSizeClass(UIUserInterfaceSizeClassRegular);
   }
 }
 
 bool IsCompactTabletSizeClass(UIUserInterfaceSizeClass sizeClass) {
   return IsIPadIdiom() && sizeClass == UIUserInterfaceSizeClassCompact;
 }
+
+BOOL IsRTLUILayout() {
+  if (base::ios::IsRunningOnIOS9OrLater()) {
+#if __IPHONE_9_0
+    // Calling this method is better than using the locale on iOS9 since it will
+    // work with the right to left pseudolanguage.
+    return [UIView userInterfaceLayoutDirectionForSemanticContentAttribute:
+                       UISemanticContentAttributeUnspecified] ==
+           UIUserInterfaceLayoutDirectionRightToLeft;
+#endif
+  }
+  // Using NSLocale instead of base::i18n::IsRTL() in order to take into account
+  // right to left pseudolanguage correctly (which base::i18n::IsRTL() doesn't).
+  return
+      [NSLocale
+          characterDirectionForLanguage:
+              [[NSLocale currentLocale] objectForKey:NSLocaleLanguageCode]] ==
+      NSLocaleLanguageDirectionRightToLeft;
+}