Change the iOS Web UI font to Roboto.

BUG=429941

Review URL: https://codereview.chromium.org/687653003

Cr-Commit-Position: refs/heads/master@{#302678}

ui/strings/app_locale_settings.grd

@@ -218,7 +218,7 @@
           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
@@ -229,6 +229,17 @@
           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. -->