Change the iOS Web UI font to Roboto.

ui/strings/app_locale_settings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 <grit latest_public_release="0" current_release="1">
   <outputs>
     <output filename="grit/app_locale_settings.h" type="rc_header">
       <emit emit_type='prepend'></emit>
     </output>
     <output filename="app_locale_settings_am.pak" type="data_package" lang="am" />
     <output filename="app_locale_settings_ar.pak" type="data_package" lang="ar" />
     <if expr="use_third_party_translations">
       <output filename="app_locale_settings_ast.pak" type="data_package" lang="ast" />
@@ skipping 200 matching lines @@
         <!-- The relative font size in % used in Web UI (e.g. History).  -->
         <message name="IDS_WEB_FONT_SIZE" use_name_for_id="true">
           75%
         </message>
         <!-- The relative font size in % used in web-style native pages
         on Windows earlier than Vista (e.g. History).  -->
         <message name="IDS_WEB_FONT_SIZE_XP" use_name_for_id="true">
           75%
         </message>
       </if>
-      <if expr="is_macosx or is_ios">
+      <if expr="is_macosx">
         <!-- The font used in Web UI (e.g. History). -->
         <message name="IDS_WEB_FONT_FAMILY" use_name_for_id="true">
           'Lucida Grande', sans-serif
         </message>
 
         <!-- The relative font size in % used in Web UI (e.g. History).  -->
         <message name="IDS_WEB_FONT_SIZE" use_name_for_id="true">
           75%
         </message>
       </if>
+      <if expr="is_ios">
+        <!-- The font used in Web UI (e.g. History). -->
+        <message name="IDS_WEB_FONT_FAMILY" use_name_for_id="true">
+          'Roboto-Regular', sans-serif
+        </message>
+
+        <!-- The relative font size in % used in Web UI (e.g. History).  -->
+        <message name="IDS_WEB_FONT_SIZE" use_name_for_id="true">
+          75%
+        </message>
+      </if>
       <if expr="(is_linux or is_android or is_bsd) and not chromeos">
         <!-- The font used in Web UI (e.g. History). Note that these are only
              backups. We try to use the system font if possible. -->
         <message name="IDS_WEB_FONT_FAMILY" use_name_for_id="true">
           Arial, sans-serif
         </message>
 
         <!-- The relative font size in % used in Web UI (e.g. History).  -->
         <message name="IDS_WEB_FONT_SIZE" use_name_for_id="true">
           75%
@@ skipping 12 matching lines @@
         </message>
 
         <!-- The relative font size in % used in Web UI (e.g. History).  -->
         <message name="IDS_WEB_FONT_SIZE" use_name_for_id="true">
           75%
         </message>
       </if>
     </messages>
   </release>
 </grit>