Add quiet safe browsing interstitial for WebView

components/security_interstitials/core/browser/resources/interstitial_common.css

+/* Copyright 2017 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. */
+
+a {
+  color: #585858;
+}
+
+body {
+  background-color: #f7f7f7;
+  color: #646464;

[felt, 2017/05/05 04:35:01]

I think the preferred Chrome style is rgb for colors. However I know this is a
refactor and this was previously done with the hex #. (Dan would know.)

+}
+
+#details-button {
+  background: inherit;
+  border: 0;
+  float: none;
+  margin: 0;
+  padding: 10px 0;
+  text-transform: uppercase;
+}
+
+.hidden {
+  display: none;
+}
+
+html {
+  -webkit-text-size-adjust: 100%;
+  font-size: 125%;
+}
+
+.icon {
+  background-repeat: no-repeat;
+  background-size: 100%;
+}