bluetooth: Add basic scanning to chrome://bluetooth-internals.

chrome/browser/resources/bluetooth_internals/bluetooth_internals.css

 /* Copyright 2016 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 :root {
   --fade-duration: 225ms;
+  --header-height: 48px;
   --md-timing-function: cubic-bezier(.4, 0, .6, 1);
   --sidebar-width: 155px;
   --sidebar-neg-width: calc(var(--sidebar-width) * -1);
 }
 
 html,
 body {
   margin: 0;
   padding: 0;
 }
@@ skipping 11 matching lines @@
   #page-container {
     -webkit-margin-start: 0;
   }
 }
 
 /* Page content */
 #page-container section {
   padding: 24px 16px;
 }
 
+#page-container .header-extras {
+  -webkit-margin-end: 16px;
+  -webkit-margin-start: var(--sidebar-width);
+  align-items: flex-end;
+  display: flex;
+  height: var(--header-height);
+  justify-content: flex-end;
+  left: 0;
+  position: fixed;
+  right: 0;
+  top: 0;
+}
+
 /* Page header */
 .page-header {
   align-items: center;
   background-color: white;
   border-bottom: 1px solid #eee;
   display: flex;
-  height: 48px;
+  height: var(--header-height);
   padding-top: 8px;
   position: sticky;
   top: 0;
 }
 
 .page-header > h1 {
   margin: 13px 0;
 }
 
 #menu-btn {
@@ skipping 221 matching lines @@
 
 .snackbar.error {
   background-color: rgb(244, 67, 54);
 }
 
 .snackbar.open {
   opacity: 1;
   transform: translate3d(0, 0, 0);
   visibility: visible;
 }