MD Settings: convert paper-icon-button to paper-icon-button-light.

chrome/browser/resources/settings/people_page/change_picture.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/util.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-a11y-keys/iron-a11y-keys.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-selector/iron-selector.html">
-<link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
+<link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../icons.html">
 <link rel="import" href="camera.html">
 <link rel="import" href="change_picture_browser_proxy.html">
 <link rel="import" href="../route.html">
 <link rel="import" href="../settings_shared_css.html">
 
 <dom-module id="settings-change-picture">
   <template>
     <style include="settings-shared">
@@ skipping 109 matching lines @@
               [[getAuthorWebsite_(selectedItem_, defaultImages_)]]
             </a>
           </div>
         </template>
       </div>
       <div id="previewPane">
         <img alt="$i18n{previewAltText}" src="[[selectedItem_.src]]"
             hidden="[[isPreviewImageHidden_(selectedItem_)]]">
         <div id="discardControlBar"
             hidden="[[isDiscardHidden_(selectedItem_)]]">
-          <paper-icon-button id="discardOldImage" tabindex="0"
-              icon="cr:delete" title="$i18n{discardPhoto}"
+          <button is="paper-icon-button-light" id="discardOldImage"
+              tabindex="0" class="icon-delete" title="$i18n{discardPhoto}"

[Dan Beam, 2017/05/23 16:36:22]

do you still need a tabindex=0 here?

[scottchen, 2017/05/27 00:18:03]

nope

               on-tap="onTapDiscardOldImage_">
-          </paper-icon-button>
+          </button>
         </div>
         <settings-camera id="camera"
             camera-active="[[isCameraActive_(cameraPresent_, selectedItem_)]]"
             on-phototaken="onPhotoTaken_">
         </settings-camera>
       </div>
     </div>
   </template>
   <script src="change_picture.js"></script>
 </dom-module>