Adds initial key systems support for Chromecast.

chromecast/media/base/key_systems_common.h

Index: chromecast/media/base/key_systems_common.h
diff --git a/chromecast/media/base/key_systems_common.h b/chromecast/media/base/key_systems_common.h
new file mode 100644
index 0000000000000000000000000000000000000000..b91c167e97405f61818a6f94b62ade892e0a2408
--- /dev/null
+++ b/chromecast/media/base/key_systems_common.h
@@ -0,0 +1,26 @@
+// 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 CHROMECAST_MEDIA_BASE_KEY_SYSTEMS_COMMON_H_
+#define CHROMECAST_MEDIA_BASE_KEY_SYSTEMS_COMMON_H_
+
+#include <string>
+
+namespace chromecast {
+
+extern const char* kPlayreadyKeySystems[];
+extern const char kUnsupportedClearKeySystem[];
+
+enum CastKeySystem {
+  KEY_SYSTEM_NONE = 0,
+  KEY_SYSTEM_CLEAR_KEY,
+  KEY_SYSTEM_PLAYREADY,
+  KEY_SYSTEM_WIDEVINE
+};
+
+CastKeySystem GetKeySystemByName(const std::string& key_system_name);
+
+}  // namespace chromecast
+
+#endif  // CHROMECAST_MEDIA_BASE_KEY_SYSTEMS_COMMON_H_