Upstreaming browser/ui/uikit_ui_util from iOS.

Added AddSameCenterXConstraint which add constraints to a
parent view to horizontally align two subviews.
Added BOOL IsRTLUILayout() which take into account RTL pseudo
language. This will be removed once base::i18n::IsRTL() supports it.

BUG=None

Review URL: https://codereview.chromium.org/1280913003

Cr-Commit-Position: refs/heads/master@{#342328}

2 files changed, 47 insertions, 0 deletions

diff --git a/ios/chrome/browser/ui/uikit_ui_util.h b/ios/chrome/browser/ui/uikit_ui_util.h
index 56bad29..5bffe39 100644
--- a/ios/chrome/browser/ui/uikit_ui_util.h
+++ b/ios/chrome/browser/ui/uikit_ui_util.h
@@ -142,6 +142,12 @@ void ApplyVisualConstraintsWithMetrics(NSArray* constraints,
 // |subview| must be a subview of |parentView|.
 void AddSameCenterXConstraint(UIView* parentView, UIView* subview);
 
+// Adds a constraint that |subview1| and |subview2| are center aligned
+// horizontally on |parentView|.
+// |subview1| and |subview2| must be subview of |parentView|.
+void AddSameCenterXConstraint(UIView *parentView, UIView *subview1,
+                              UIView *subview2);
+
 // Adds a constraint that |subview| is center aligned vertically in
 // |parentView|.
 // |subview| must be a subview of |parentView|.
@@ -153,6 +159,13 @@ void AddSameCenterYConstraint(UIView* parentView, UIView* subview);
 void AddSameCenterYConstraint(UIView* parentView,
                               UIView* subview1,
                               UIView* subview2);
+// Whether the UI is configured for right to left layout.
+// The implementation will use the local in order to get the UI layout direction
+// for version of iOS under 9.
+// TODO(jbbegue): Use base::i18n::IsRTL() instead when it will support RTL
+// pseudo language. Remove that method once base::i18n::IsRTL() is fixed.
+// crbug/514625.
+BOOL IsRTLUILayout();
 
 // Returns true if the main application window's rootViewController is a compact
 // iPad horizontal size class.
diff --git a/ios/chrome/browser/ui/uikit_ui_util.mm b/ios/chrome/browser/ui/uikit_ui_util.mm
index 3f8d5b7..9b9d8f5 100644
--- a/ios/chrome/browser/ui/uikit_ui_util.mm
+++ b/ios/chrome/browser/ui/uikit_ui_util.mm
@@ -457,6 +457,21 @@ void AddSameCenterXConstraint(UIView* parentView, UIView* subview) {
                                           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
@@ -499,3 +514,22 @@ bool IsCompactTablet() {
 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;
+}