Add Widevine CDM support (issue #1631)

- Windows/Mac: Use `--enable-widevine-cdm` command-line flag to
  enable download of CDM binaries via the component updater.
- Linux: Use `--widevide-cdm-path` and `--widevine-cdm-version`
  command-line flags to load CDM binaries that already exist on
  the system.
- A cache-path value is usually required when CDM is enabled.

libcef/browser/component_updater/cef_component_updater_configurator.h

@@ -0,0 +1,28 @@
+// 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.
+
+#ifndef LIBCEF_BROWSER_COMPONENT_UPDATER_CEF_COMPONENT_UPDATER_CONFIGURATOR_H_
+#define LIBCEF_BROWSER_COMPONENT_UPDATER_CEF_COMPONENT_UPDATER_CONFIGURATOR_H_
+
+#include "base/memory/ref_counted.h"
+#include "components/update_client/configurator.h"
+
+namespace base {
+class CommandLine;
+}
+
+namespace net {
+class URLRequestContextGetter;
+}
+
+namespace component_updater {
+
+scoped_refptr<update_client::Configurator>
+MakeCefComponentUpdaterConfigurator(
+    const base::CommandLine* cmdline,
+    net::URLRequestContextGetter* context_getter);
+
+}  // namespace component_updater
+
+#endif  // LIBCEF_BROWSER_COMPONENT_UPDATER_CEF_COMPONENT_UPDATER_CONFIGURATOR_H_