MD Settings: show part of a11y page on Mac/Windows/Linux

chrome/browser/resources/settings/a11y_page/a11y_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
+<if expr="chromeos">
 <link rel="import" href="chrome://md-settings/controls/settings_checkbox.html">
+</if>
 <link rel="import" href="chrome://md-settings/settings_shared_css.html">
 
 <dom-module id="settings-a11y-page">
   <template>
     <style include="settings-shared"></style>
     <div class="settings-box row first">
+<if expr="chromeos">
       <span i18n-content="a11yExplanation"></span>
       <a i18n-values="href:a11yLearnMoreUrl" i18n-content="learnMore"
           target="_blank"></a>
     </div>
 
     <div class="settings-box block">
       <settings-checkbox i18n-values="label:optionsInMenuLabel"
           pref="{{prefs.settings.a11y.enable_menu}}">
       </settings-checkbox>
       <settings-checkbox i18n-values="label:largeMouseCursorLabel"
@@ skipping 51 matching lines @@
         <settings-checkbox pref="{{prefs.settings.a11y.select_to_speak}}"
             i18n-values="label:selectToSpeakLabel">
         </settings-checkbox>
         <settings-checkbox pref="{{prefs.settings.a11y.switch_access}}"
             i18n-values="label:switchAccessLabel">
         </settings-checkbox>
       </template>
     </div>
 
     <div class="settings-box">
+</if>

[tommycli, 2016/03/25 18:16:51]

I had to do a double-take to understand the <if> structure in this file. Could
we if-out the whole first two divs as chromeos-only and change the last div to:

<if expr="chromeos">
  <div class="settings-box">
</if>
<if expr="not chromeos">
  <div class="settings-box row first">
</if>
?

[Dan Beam, 2016/03/25 18:49:17]

Done.

       <div class="button-strip">
-        <paper-button i18n-content="moreFeaturesLink"
+        <paper-button i18n-content="moreFeaturesLink" class="primary-button"
             on-tap="onMoreFeaturesTap_"></paper-button>
       </div>
     </div>
   </template>
   <script src="a11y_page.js"></script>
 </dom-module>