Ensure strikethrough font renders in omnibox on iOS 10.3

ios/chrome/browser/ui/omnibox/omnibox_view_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.
 
 #include "ios/chrome/browser/ui/omnibox/omnibox_view_ios.h"
 
 #import <CoreText/CoreText.h>
 #import <MobileCoreServices/MobileCoreServices.h>
 
 #include "base/auto_reset.h"
@@ skipping 653 matching lines @@
 
   if ((security_level == security_state::NONE) ||
       (security_level == security_state::HTTP_SHOW_WARNING)) {
     return;
   }
 
   DCHECK_NE(security_state::SECURITY_WARNING, security_level);
   DCHECK_NE(security_state::SECURE_WITH_POLICY_INSTALLED_CERT, security_level);
 
   if (security_level == security_state::DANGEROUS) {
+    // Workaround: Add an attribute to allow strikethough to apply on iOS 10.3.

[rohitrao (ping after 24h), 2017/04/06 14:51:21]

Should we only apply this attribute if running on 10.3 and above?  Is there any
chance this could break behavior on older OS versions?

+    // See https://crbug.com/699702 for discussion.
+    [attributing_display_string_
+        addAttribute:NSBaselineOffsetAttributeName
+               value:@0
+               range:NSMakeRange(0, [attributing_display_string_ length])];
+
     // Add a strikethrough through the scheme.
     [attributing_display_string_
         addAttribute:NSStrikethroughStyleAttributeName
                value:[NSNumber numberWithInteger:NSUnderlineStyleSingle]
                range:range.ToNSRange()];
   }
 
   UIColor* color = GetSecureTextColor(security_level, [field_ incognito]);
   if (color) {
     [attributing_display_string_ addAttribute:NSForegroundColorAttributeName
@@ skipping 189 matching lines @@
 // is being left out for now because it was not present before the OmniboxView
 // rewrite.
 #if 0
   // When editing is in progress, the url text is not colored, so there is
   // nothing to emphasize.  (Calling SetText() in that situation would also be
   // harmful, as it would reset the carat position to the end of the text.)
   if (!IsEditingOrEmpty())
     SetText(GetText());
 #endif
 }