Fix text alignment issue in Chrome iOS' omnibox.

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

 // Copyright (c) 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/omnibox/omnibox_text_field_ios.h"
 
 #import <CoreText/CoreText.h>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 255 matching lines @@
 
     if ([NSLocale characterDirectionForLanguage:lang] ==
         NSLocaleLanguageDirectionRightToLeft) {
       return NSTextAlignmentRight;
     }
   }
   return NSTextAlignmentLeft;
 }
 
 - (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 {
   // If the pre-edit text is wider than the omnibox, right-align the text so it
   // ends at the same x coord as the blue selection box.
   CGSize textSize =
       [_preEditStaticLabel.text cr_pixelAlignedSizeWithFont:_font];
   BOOL isLTR = [self bestTextAlignment] == NSTextAlignmentLeft;
   return textSize.width < _preEditStaticLabel.frame.size.width
              ? (isLTR ? NSTextAlignmentLeft : NSTextAlignmentRight)
@@ skipping 744 matching lines @@
   // Disable the RTL arrow menu item. The omnibox sets alignment based on the
   // text in the field, and should not be overridden.
   if ([NSStringFromSelector(action) hasPrefix:@"makeTextWritingDirection"]) {
     return NO;
   }
 
   return [super canPerformAction:action withSender:sender];
 }
 
 @end