[ios] Workaround error affecting 3rd party keyboards and 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/ios/ios_util.h"
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
 
 #include "base/strings/sys_string_conversions.h"
 #include "components/grit/components_scaled_resources.h"
 #include "components/omnibox/browser/autocomplete_input.h"
+#include "ios/chrome/browser/application_context.h"
 #include "ios/chrome/browser/autocomplete/autocomplete_scheme_classifier_impl.h"
+#include "ios/chrome/browser/experimental_flags.h"
 #import "ios/chrome/browser/ui/animation_util.h"
 #include "ios/chrome/browser/ui/omnibox/omnibox_util.h"
 #import "ios/chrome/browser/ui/reversed_animation.h"
 #include "ios/chrome/browser/ui/rtl_geometry.h"
 #include "ios/chrome/browser/ui/ui_util.h"
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
 #import "ios/chrome/common/material_timing.h"
 #include "ios/chrome/grit/ios_strings.h"
 #include "ios/chrome/grit/ios_theme_resources.h"
 #include "skia/ext/skia_utils_ios.h"
@@ skipping 423 matching lines @@
     [autocompleteText
         addAttribute:NSBackgroundColorAttributeName
                value:[self selectedTextBackgroundColor]
                range:NSMakeRange([fieldText length], autocompleteLength)];
     [_selection setAttributedText:autocompleteText];
     [_selection setTextAlignment:[self bestTextAlignment]];
   } else {
     [self clearAutocompleteText];
   }
 
-  self.attributedText = fieldText;
+  BOOL updateText = YES;
+  if (experimental_flags::IsThirdPartyKeyboardWorkaroundEnabled() &&
+      GetApplicationContext()->GetApplicationLocale() == "ja") {

[rohitrao (ping after 24h), 2017/06/27 13:48:47]

This should check the primaryLanguage of the current input, not the application
locale.

+    updateText =
+        (!self.editing || ![self.text isEqualToString:fieldText.string]);

[rohitrao (ping after 24h), 2017/06/27 13:48:47]

I think I'm ok with this, for two reasons:
1) We set a number of attributes in the omnibox, but the only ones that vary are
the foreground and background colors.  Other attributes (like font, style, etc)
are set for the entire string, and a few (strikethrough) are only set when not
editing.
2) setAttributedText always forces the color of the string when editing, so any
color attributes here would be ignored anyways.

Can you capture the gist of what I wrote above in a comment somewhere?

+  }
+  if (updateText) {
+    self.attributedText = fieldText;
+  }
 
   // iOS changes the font to .LastResort when some unexpected unicode strings
   // are used (e.g. 𝗲𝗺𝗽𝗵𝗮𝘀𝗶𝘀).  Setting the NSFontAttributeName in the
   // attributed string to -systemFontOfSize fixes part of the problem, but the
   // baseline changes so text is out of alignment.
   [self setFont:_font];
   // TODO(justincohen): Find a better place to put this, and consolidate it with
   // the same call in omniboxViewIOS.
   [self updateTextDirection];
 }
@@ skipping 465 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