Remove ::shadow and /deep/ combinator from Files app.

ui/file_manager/gallery/css/gallery.css

 /* Copyright (c) 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. */
 
 body {
   -webkit-user-select: none;
   background-color: black;
   font-size: 84%;
   margin: 0;
 }
@@ skipping 58 matching lines @@
 
 html[dir='rtl'] .bubble .close-x {
   right: auto;
   left: 3px;
 }
 
 .bubble .close-x:hover {
   opacity: 0.7;
 }
 
-paper-ripple,
-paper-button::shadow paper-ripple {
+paper-ripple {
   color: black;
 }
 
-files-toggle-ripple::shadow .ripple.activated {
-  opacity: 0.4;
-}
-
 .gallery,
 .gallery > .content {
   bottom: 0;
   left: 0;
   overflow: hidden;
   position: absolute;
   right: 0;
   top: 0;
 }
 
@@ skipping 451 matching lines @@
 .gallery[editing] .edit-mode-toolbar .options,
 .gallery[editing] .edit-mode-toolbar .exit-button-spacer {
   opacity: 1;
   visibility: visible;
 }
 
 .edit-mode-toolbar .overwrite-original {
   -webkit-margin-start: 16px;
 }
 
-.edit-mode-toolbar .overwrite-original[disabled]::shadow #checkbox,
-.edit-mode-toolbar .overwrite-original[disabled]::shadow #checkboxLabel {
+.edit-mode-toolbar .overwrite-original[disabled] {
   opacity: 0.2;
 }
 
 .gallery .edit-mode-toolbar .saved {
   -webkit-margin-start: 14px;
   cursor: inherit;
   opacity: 0;
   pointer-events: none;
   transition-duration: 120ms;
   transition-property: opacity, transform;
@@ skipping 337 matching lines @@
   -webkit-margin-end: 8px;
   display: block;
   height: 16px;
   width: 16px;
 }
 
 paper-slider {
   width: 172px;
 }
 
-paper-slider::shadow paper-progress::shadow #progressContainer {
-  background-color: rgba(255, 255, 255, 0.2);
-}
-
 .edit-modal .range.brightness > .icon {
   background-image: -webkit-image-set(
       url(../images/100/brightness.png) 1x,
       url(../images/200/brightness.png) 2x);
 }
 
 .edit-modal .range.contrast > .icon {
   background-image: -webkit-image-set(
       url(../images/100/contrast.png) 1x,
       url(../images/200/contrast.png) 2x);
@@ skipping 448 matching lines @@
 .thumbnail-view .animation-thumbnail {
   background-repeat: no-repeat;
   background-size: cover;
   display: none;
   position: absolute;
 }
 
 .thumbnail-view .animation-thumbnail.animating {
   display: block;
 }