Add quiet safe browsing interstitial for WebView

components/security_interstitials/core/browser/resources/interstitial_webview_quiet.js

Index: components/security_interstitials/core/browser/resources/interstitial_webview_quiet.js
diff --git a/components/security_interstitials/core/browser/resources/interstitial_webview_quiet.js b/components/security_interstitials/core/browser/resources/interstitial_webview_quiet.js
new file mode 100644
index 0000000000000000000000000000000000000000..cb189d7128a27e5ff10207902dae683dac6b0792
--- /dev/null
+++ b/components/security_interstitials/core/browser/resources/interstitial_webview_quiet.js
@@ -0,0 +1,10 @@
+// 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.
+
+function initPage() {
+  var isGiantWebView = loadTimeData.getBoolean('is_giant');
+  document.body.className = isGiantWebView ? 'giant' : '';
+}
+
+document.addEventListener('DOMContentLoaded', initPage);