MD Settings: use theme homepage URLs when set

chrome/browser/resources/settings/appearance_page/appearance_page.html

 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="/appearance_page/appearance_browser_proxy.html">
 <link rel="import" href="/controls/controlled_radio_button.html">
 <link rel="import" href="/controls/settings_dropdown_menu.html">
 <link rel="import" href="/controls/settings_input.html">
@@ skipping 24 matching lines @@
         <div class="settings-box first two-line" id="wallpaperButton"
             on-tap="openWallpaperManager_" actionable
             hidden="[[!pageVisibility.setWallpaper]]">
           <div class="start">
             $i18n{setWallpaper}
             <div class="secondary">$i18n{openWallpaperApp}</div>
           </div>
           <button class="icon-external" is="paper-icon-button-light"></button>
         </div>
         <div class="settings-box two-line"
-            hidden="[[!pageVisibility.setTheme]]" actionable>
+            hidden="[[!pageVisibility.setTheme]]">
 </if>
 <if expr="not chromeos">
         <div class="settings-box two-line first"
-            hidden="[[!pageVisibility.setTheme]]" actionable>
+            hidden="[[!pageVisibility.setTheme]]">
 </if>
-          <div class="start two-line" on-tap="openThemesGallery_">
+          <div class="start two-line" on-tap="onThemesTap_" actionable>
             <div class="flex">
               <div>$i18n{themes}</div>
               <div class="secondary">[[themeSublabel_]]</div>
             </div>
             <button class="icon-external" is="paper-icon-button-light"></button>
           </div>
 <if expr="not is_linux or chromeos">
           <template is="dom-if" if="[[prefs.extensions.theme.id.value]]">
             <div class="secondary-action">
               <paper-button id="useDefault" on-tap="onUseDefaultTap_"
@@ skipping 94 matching lines @@
             associated-control="[[$$('#customize-fonts-subpage-trigger')]]"
             page-title="$i18n{customizeFonts}">
           <settings-appearance-fonts-page prefs="{{prefs}}">
           </settings-appearance-fonts-page>
         </settings-subpage>
       </template>
     </settings-animated-pages>
   </template>
   <script src="appearance_page.js"></script>
 </dom-module>