Fix text alignment issue in Chrome iOS' omnibox.

ios/chrome/browser/ui/omnibox/omnibox_text_field_ios.mm

Index: ios/chrome/browser/ui/omnibox/omnibox_text_field_ios.mm
diff --git a/ios/chrome/browser/ui/omnibox/omnibox_text_field_ios.mm b/ios/chrome/browser/ui/omnibox/omnibox_text_field_ios.mm
index 64020a711201f11c6d7ae81db8e1fc1865d881df..fa657bb2b238adea142bbbfbdac766949bd4b19e 100644
--- a/ios/chrome/browser/ui/omnibox/omnibox_text_field_ios.mm
+++ b/ios/chrome/browser/ui/omnibox/omnibox_text_field_ios.mm
@@ -273,10 +273,14 @@ NSString* const kOmniboxFadeAnimationKey = @"OmniboxFadeAnimation";
 }
 
 - (NSTextAlignment)bestTextAlignment {
+  NSTextAlignment alignment;
   if ([self isFirstResponder]) {
-    return [self bestAlignmentForText:[self text]];
+    alignment = [self bestAlignmentForText:[self text]];
+  } else {
+    alignment = UseRTLLayout() ? NSTextAlignmentRight : NSTextAlignmentLeft;
   }
-  return NSTextAlignmentNatural;
+  DCHECK(alignment == NSTextAlignmentLeft || alignment == NSTextAlignmentRight);
+  return alignment;
 }
 
 - (NSTextAlignment)preEditTextAlignment {