[ios] Fix omnibox baseWritingDirection and dismissal iOS11 bugs.

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 536 matching lines @@
 // but there are numerous edge case issues with it, so it's simpler to just
 // manually update the text alignment and writing direction of the UITextField.
 - (void)updateTextDirection {
   // Setting the empty field to Natural seems to let iOS update the cursor
   // position when the keyboard language is changed.
   if (![self text].length) {
     [self setTextAlignment:NSTextAlignmentNatural];
     return;
   }
 
-  NSTextAlignment alignment = [self bestTextAlignment];
+  NSTextAlignment alignment = [self bestAlignmentForText:[self text]];

[rohitrao (ping after 24h), 2017/06/12 22:08:52]

Why is it ok to always use [self text] here?

Is this better or worse than updating this function to properly handle Natural
alignments?

   [self setTextAlignment:alignment];
   UITextWritingDirection writingDirection =
       alignment == NSTextAlignmentLeft ? UITextWritingDirectionLeftToRight
                                        : UITextWritingDirectionRightToLeft;
   [self
       setBaseWritingDirection:writingDirection
                      forRange:[self
                                   textRangeFromPosition:[self
                                                             beginningOfDocument]
                                              toPosition:[self endOfDocument]]];
@@ skipping 447 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