linux_aura: Three fixes for switching themes.

chrome/browser/resources/options/browser_options.html

 <div id="settings" class="page" hidden>
   <header>
     <h1 i18n-content="settingsTitle"></h1>
   </header>
 <if expr="not pp_ifdef('chromeos')">
   <include src="sync_section.html">
 </if>
 <if expr="pp_ifdef('chromeos')">
   <section>
     <h3 i18n-content="sectionTitleInternet"></h3>
@@ skipping 13 matching lines @@
 <if expr="not pp_ifdef('chromeos')">
   <include src="startup_section.html">
 </if>
   <section>
     <h3 i18n-content="sectionTitleAppearance"></h3>
     <div class="settings-row">
 <if expr="pp_ifdef('chromeos')">
       <button id="set-wallpaper" i18n-content="setWallpaper"
           guest-visibility="disabled"></button>
 </if>
-<if expr="not pp_ifdef('toolkit_views') and is_posix and not is_macosx">
+<if expr="not pp_ifdef('chromeos') and is_posix and not is_macosx">
       <button id="themes-gallery" i18n-content="themesGallery"></button>
-      <button id="themes-GTK-button"
-          i18n-content="themesGTKButton"></button>
+      <button id="themes-native-button"
+          i18n-content="themesNativeButton"></button>
       <button id="themes-reset"
           i18n-content="themesSetClassic"></button>
 </if>
-<if expr="pp_ifdef('toolkit_views') or is_win or is_macosx">
+<if expr="pp_ifdef('chromeos') or is_win or is_macosx">
       <button id="themes-gallery" i18n-content="themesGallery"></button>
       <button id="themes-reset" i18n-content="themesReset"></button>
 </if>
     </div>
     <div class="checkbox" guest-visibility="disabled">
       <span class="controlled-setting-with-label">
         <input id="show-home-button" type="checkbox"
             pref="browser.show_home_button"
             metric="Options_Homepage_HomeButton">
         <span>
@@ skipping 706 matching lines @@
     </div>
   </section>
   </div>  <!-- advanced-settings-container -->
   </div>  <!-- advanced-settings -->
   <footer>
     <button id="advanced-settings-expander" class="link-button"
         i18n-content="showAdvancedSettings">
     </button>
   </footer>
   </div>