Adds initial key systems support for Chromecast.

chromecast/media/base/key_systems_common.cc

+// 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.
+
+#include "chromecast/media/base/key_systems_common.h"
+
+#include <cstddef>
+
+#include "widevine_cdm_version.h" // In SHARED_INTERMEDIATE_DIR.
+
+namespace media {

[lcwu1, 2014/09/15 18:09:50]

s/media/chromecast

[gunsch, 2014/09/15 21:43:37]

Done.

+
+const char kClearKeySystem[] = "org.w3.clearkey";

[ddorwin, 2014/09/13 03:27:06]

Ideally, these names would only be in one place.

[gunsch, 2014/09/15 21:43:38]

This is the only location they're in for chromecast/. Removed duplicate with
media::kClearKey, however.

+const char kUnsupportedClearKeySystem[] = "unsupported-org.w3.clearkey";

[ddorwin, 2014/09/13 03:27:06]

You don't need this. The intent of this is to cause a not-supported error when
mixing prefixed and unprefixed API and name.

[gunsch, 2014/09/15 21:43:38]

I think we currently expect those to be mixed (see other comment), partly
because we don't yet support the unprefixed EME API. 

Added a TODO.

+
+const char* kPlayreadyKeySystems[] = {
+  "com.chromecast.playready",
+  NULL
+};
+
+CastKeySystem GetKeySystemByName(const std::string& key_system_name) {
+#if defined(WIDEVINE_CDM_AVAILABLE)
+  if (key_system_name.compare(kWidevineKeySystem) == 0) {
+    return KEY_SYSTEM_WIDEVINE;
+  }
+#endif  // defined(WIDEVINE_CDM_AVAILABLE)
+
+#if defined(PLAYREADY_CDM_AVAILABLE)
+  for (size_t i = 0; kPlayreadyKeySystems[i] != NULL; i++) {
+    if (key_system_name.compare(kPlayreadyKeySystems[i]) == 0) {

[ddorwin, 2014/09/13 03:27:06]

Use arraysize() instead of NULL marker

[gunsch, 2014/09/15 21:43:38]

This list is exposed to other files (notably key_systems_cast.cc). Can't use
arraysize macro when included from elsewhere.

[ddorwin, 2014/09/15 22:50:53]

You should be able to expose a size constant that is declared in the header and
defined in the .cc file just like the array.

[gunsch, 2014/09/16 16:57:59]

Done.

+      return KEY_SYSTEM_PLAYREADY;
+    }
+  }
+#endif  // defined(PLAYREADY_CDM_AVAILABLE)
+
+  if (key_system_name.compare(kClearKeySystem) == 0 ||
+      key_system_name.compare(kUnsupportedClearKeySystem) == 0) {
+    return KEY_SYSTEM_CLEAR_KEY;
+  }
+
+  return KEY_SYSTEM_NONE;
+}
+
+}  // namespace media