ui/file_manager/file_manager/foreground/elements/files_ripple.html

<!-- Copyright 2015 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.
  -->

<link rel="import" href="chrome://resources/html/polymer.html">

<dom-module id="files-ripple">
  <template>
    <style>
      :host {
        align-items: center;
        display: flex;
        height: 200%;
        left: -50%;
        pointer-events: none;
        position: absolute;
        top: -50%;
        width: 200%;
      }

      .ripple {
        background-color: var(--files-ripple-bg-color, white);
        border-radius: 50%;
        height: 50%;
        margin: 0 auto;
        opacity: 0;
        width: 50%;
        @apply(--files-ripple);
      }

      :host([pressed]) .ripple {
        opacity: 0.2;
      }
    </style>
    <div id="ripple" class="ripple"></div>
  </template>
</dom-module>

<script src="files_ripple.js"></script>