MD Settings: <settings-dialog>, restore focus effect for the cancel button.

chrome/browser/resources/settings/settings_shared_css.html

 <!-- Common styles for Material Design settings. -->
 <dom-module id="settings-shared">
   <template>
     <style>
       :root {
         --checkbox-margin-start: 2px;
         --checkbox-size: 16px;
         --checkbox-spacing: 18px;
         --iron-icon-fill-color: var(--paper-grey-600);
         --iron-icon-height: 20px;
@@ skipping 111 matching lines @@
         margin-top: 25px;
       }
 
       .button-strip {
         text-align: end;
       }
 
       .action-button {
         background: var(--google-blue-500);
         color: white;
-        font-weight: 500;
       }
 
       .action-button[disabled] {
         opacity: .25;  /* TODO(dbeam): check this value with bettes. */
       }
 
+      .action-button,
+      .cancel-button {
+        font-weight: 500;
+      }
+
       .list-frame {
         @apply(--layout-center);
         -webkit-padding-end: 20px;
         -webkit-padding-start: 48px;
         display: block;
         padding-bottom: 0;
         padding-top: 0;
       }
 
       .list-frame .secondary,
@@ skipping 105 matching lines @@
 
       .settings-checkbox-spacer {
         -webkit-margin-start: calc(
             var(--checkbox-margin-start) +
             var(--checkbox-size) +
             var(--checkbox-spacing));
       }
     </style>
   </template>
 </dom-module>