[MD-Settings] Make the Advanced button into an actual button.

chrome/browser/resources/settings/settings_main/settings_main.html

 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/html/promise_resolver.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
+<link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="/about_page/about_page.html">
 <link rel="import" href="/advanced_page/advanced_page.html">
 <link rel="import" href="/basic_page/basic_page.html">
 <link rel="import" href="/route.html">
 <link rel="import" href="/settings_page/main_page_behavior.html">
 <link rel="import" href="/settings_vars_css.html">
 
 <dom-module id="settings-main">
   <template>
     <style>
       #advancedToggle {
+        --paper-button: {
+          text-transform: none;
+        }
         @apply(--settings-actionable);
         align-items: center;
         display: flex;
         margin-bottom: 3px;
         margin-top: 12px;  /* Part of a 48px spacer (33px + 12px + 3px). */
         min-height: 32px;
         padding: 0 12px;
       }
 
       #overscroll {
@@ skipping 36 matching lines @@
           page-visibility="[[pageVisibility]]"
           on-subpage-expand="onSubpageExpand_">
       </settings-basic-page>
     </template>
     <template is="dom-if"
         if="[[showAdvancedSettings_(pageVisibility.advancedSettings)]]">
       <template is="dom-if" if="[[showAdvancedToggle_(
           showPages_.basic, hasExpandedSection_, previousShowPages_)]]">
         <div id="toggleSpacer"></div>
         <div id="toggleContainer">
-          <div id="advancedToggle" on-tap="toggleAdvancedPage_">

[Dan Beam, 2016/09/02 21:30:55]

could we just use role="button" or <button> instead?  i don't know that we want
a ripple on this

[hcarmona, 2016/09/02 21:55:19]

Checked with bettes@ about ripple: http://crbug.com/643309

+          <paper-button id="advancedToggle" on-tap="toggleAdvancedPage_">
             <span>$i18n{advancedPageTitle}</span>
             <iron-icon icon="[[arrowState_(showPages_.advanced)]]"></iron-icon>
-          </div>
+          </paper-button>
         </div>
       </template>
       <template is="dom-if" if="[[showPages_.advanced]]">
         <settings-advanced-page prefs="{{prefs}}"
             page-visibility="[[pageVisibility]]"
             on-subpage-expand="onSubpageExpand_">
         </settings-advanced-page>
       </template>
     </template>
     <template is="dom-if" if="[[showPages_.about]]">
       <settings-about-page></settings-about-page>
     </template>
     <div id="overscroll" style="padding-bottom: [[overscroll_]]px"></div>
   </template>
   <script src="settings_main.js"></script>
   <script src="/search_settings.js"></script>
 </dom-module>