Add convenience methods for checking horizontal size class.

ios/chrome/browser/ui/uikit_ui_util.h

Index: ios/chrome/browser/ui/uikit_ui_util.h
diff --git a/ios/chrome/browser/ui/uikit_ui_util.h b/ios/chrome/browser/ui/uikit_ui_util.h
index db6af6c7c2fbb80141aafce47d80b519a3672651..220a8bd4076d71be24385104c197f4657658bb40 100644
--- a/ios/chrome/browser/ui/uikit_ui_util.h
+++ b/ios/chrome/browser/ui/uikit_ui_util.h
@@ -176,10 +176,16 @@ void AddSameCenterYConstraint(UIView* parentView,
                               UIView* subview1,
                               UIView* subview2);
 
+// Whether the |environment| has a compact horizontal size class.
+bool IsCompact(id<UITraitEnvironment> environment);
+
 // Whether the main application window's rootViewController has a compact
 // horizontal size class.
 bool IsCompact();
 
+// Whether the |environment| has a compact iPad horizontal size class.
+bool IsCompactTablet(id<UITraitEnvironment> environment);
+
 // Whether the main application window's rootViewController has a compact
 // iPad horizontal size class.
 bool IsCompactTablet();