[MD WebUI] Move icons used in Bookmarks and Settings to shared file.

chrome/browser/resources/settings/about_page/about_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="/about_page/about_page_browser_proxy.html">
 <link rel="import" href="/i18n_setup.html">
-<link rel="import" href="/icons.html">
 <link rel="import" href="/lifetime_browser_proxy.html">
 <link rel="import" href="/route.html">
 <link rel="import" href="/settings_page/main_page_behavior.html">
 <link rel="import" href="/settings_page/settings_animated_pages.html">
 <link rel="import" href="/settings_page/settings_section.html">
 <link rel="import" href="/settings_page_css.html">
 <link rel="import" href="/settings_shared_css.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/assert.html">
 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
@@ skipping 30 matching lines @@
 
       img {
         -webkit-margin-end: var(--about-page-image-space);
       }
 
       iron-icon {
         -webkit-margin-end: var(--about-page-image-space);
         width: 32px;  /* The width of the product-logo img. */
       }
 
-      iron-icon[icon='settings:check-circle'] {
+      iron-icon[icon='cr:check-circle'] {
         fill: var(--paper-blue-600);
       }
 
-      iron-icon[icon='settings:error'] {
+      iron-icon[icon='cr:error'] {
         fill: var(--paper-red-600);
       }
 
       .product-info {
         display: block;
         padding-bottom: 10px;
         padding-top: 10px;
       }
 
       .info-section {
@@ skipping 139 matching lines @@
               <settings-detailed-build-info></settings-detailed-build-info>
             </settings-subpage>
           </template>
 </if>
         </settings-animated-pages>
       </settings-section>
     </div>
   </template>
   <script src="about_page.js"></script>
 </dom-module>