Move the casting icon to media controls.

ui/file_manager/video_player/css/header.css

 /* Copyright 2014 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. */
 
 #video-player > .header {
   -webkit-app-region: drag;
   background: rgba(30, 30, 30, 0.8);
   border-bottom: 1px solid rgba(50, 50, 50, 0.8);
   display: flex;
   flex-direction: row;
   height: 45px;
   opacity: 1;
   pointer-events: auto;
   position: absolute;
   top: 0;
   width: 100%;
   z-index: 200;
 }
 
 #video-player > .header > #title {
   color: white;
   flex-grow: 1;
   font-size: 16px;
-  height: 16px;
+  line-height: 45px;
   overflow: hidden;
-  padding: 15px;
+  padding-left: 15px;
   text-overflow: ellipsis;
   white-space: nowrap;
 }
 
 #video-player > .header > button,
 #video-player > .header > button[disabled] {
   align-content: center;
   background-color: rgba(0, 0, 0, 0);
   background-position: center;
   background-repeat: no-repeat;
@@ skipping 25 matching lines @@
 
 #video-player > .header > button {
   -webkit-app-region: no-drag;
   -webkit-margin-end: 10px;
   cursor: default;
   height: 32px;
   min-width: 32px;
   width: 32px;
 }
 
-#video-player > .header > button.cast-button {
-  background-image: -webkit-image-set(
-      url(../images/100/cast_off.png) 1x,
-      url(../images/200/cast_off.png) 2x);
-}
-
-#video-player[casting] > .header > button.cast-button {
-  background-image: -webkit-image-set(
-      url(../images/100/cast_on.png) 1x,
-      url(../images/200/cast_on.png) 2x);
-}
-
-#video-player > .header > button.cast-button:hover {
-  background-image: -webkit-image-set(
-      url(../images/100/cast_off_hover.png) 1x,
-      url(../images/200/cast_off_hover.png) 2x);
-}
-
-#video-player[casting] > .header > button.cast-button:hover {
-  background-image: -webkit-image-set(
-      url(../images/100/cast_on_hover.png) 1x,
-      url(../images/200/cast_on_hover.png) 2x);
-}
-
-#video-player > .header > button.cast-button {
-  display: none;
-}
-
-#video-player[cast-available][castable] > .header > button.cast-button {
-  display: block;
-}
-
 #video-player > .header > button.minimize-button {
   background-image: -webkit-image-set(
       url(chrome://resources/images/apps/topbar_button_minimize.png) 1x,
       url(chrome://resources/images/2x/apps/topbar_button_minimize.png) 2x);
 }
 
 #video-player > .header > button.maximize-button {
   background-image: -webkit-image-set(
       url(chrome://resources/images/apps/topbar_button_maximize.png) 1x,
       url(chrome://resources/images/2x/apps/topbar_button_maximize.png) 2x);
 }
 
 #video-player > .header > button.close-button {
   background-image: -webkit-image-set(
       url(chrome://resources/images/apps/topbar_button_close.png) 1x,
       url(chrome://resources/images/2x/apps/topbar_button_close.png) 2x);
 }