Adding search widget UI and functionality.

ios/chrome/search_widget_extension/ui_util.mm

+// Copyright 2017 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 <UIKit/UIKit.h>
+
+#include "ios/chrome/search_widget_extension/ui_util.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+namespace ui_util {
+
+NSArray<NSLayoutConstraint*>* CreateSameConstraints(UIView* view1,
+                                                    UIView* view2) {
+  return @[
+    [view1.leadingAnchor constraintEqualToAnchor:view2.leadingAnchor],
+    [view1.trailingAnchor constraintEqualToAnchor:view2.trailingAnchor],
+    [view1.topAnchor constraintEqualToAnchor:view2.topAnchor],
+    [view1.bottomAnchor constraintEqualToAnchor:view2.bottomAnchor]
+  ];
+}
+
+}  // namespace ui_util