Add CdmService to keep track of CDMs

content/public/common/key_system_service.h

Index: content/public/common/key_system_service.h
diff --git a/content/public/common/key_system_service.h b/content/public/common/key_system_service.h
new file mode 100644
index 0000000000000000000000000000000000000000..d8aebf87e0d499e07d78402c977a938b19623511
--- /dev/null
+++ b/content/public/common/key_system_service.h
@@ -0,0 +1,62 @@
+// Copyright 2016 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 CONTENT_PUBLIC_COMMON_KEY_SYSTEM_SERVICE_H_

[xhwang, 2016/01/29 07:43:07]

Is there any reason we do't put this in content/public/browser/? From our
offline chat, it seems we won't use this class in the utility process, so this
will only be used by browser/ code.

+#define CONTENT_PUBLIC_COMMON_KEY_SYSTEM_SERVICE_H_
+
+#include <string>
+#include <vector>
+
+#include "base/files/file_path.h"
+#include "base/lazy_instance.h"
+#include "base/macros.h"
+#include "base/strings/string16.h"
+#include "base/version.h"
+#include "content/common/content_export.h"
+#include "content/public/common/key_system_registration.h"
+
+namespace content {
+
+class CONTENT_EXPORT KeySystemService {
+ public:
+  // Returns the KeySystemService singleton.
+  static KeySystemService* GetInstance();
+
+  // Register |key_system|, replacing any entry that may exist for it. |path|

[xhwang, 2016/01/29 07:43:07]

Register_s_; same below.

[jrummell, 2016/03/04 01:19:41]

Done.

+  // is the path to the actual CDM, and |codecs| is the list of codecs
+  // supported by this CDM.
+  void Register(const std::string& key_system,
+                const base::FilePath& path,
+                const base::string16& codecs);

[xhwang, 2016/01/29 07:43:07]

How should the list of codecs be formatted in this string?

[jrummell, 2016/03/04 01:19:41]

Converted to a std::vector<>.

+
+  // Determine the path set for |key_system|. If |key_system| has been
+  // registered, true is returned and |path| is updated. Otherwise false
+  // is returned and |path| is unchanged.
+  bool Path(const std::string& key_system, base::FilePath* path);

[xhwang, 2016/01/29 07:43:07]

Path() is a bit vague. How about GetCdmLibraryPath()?

[jrummell, 2016/03/04 01:19:41]

Done.

+
+  // Determine the codecs set for |key_system|. If |key_system| has been
+  // registered, true is returned and |codecs| is updated. Otherwise false

[xhwang, 2016/01/29 07:43:07]

Is it possible "true" is returned and "codecs" is still empty?

[jrummell, 2016/03/04 01:19:41]

Updated.

+  // is returned and |codecs| is unchanged.
+  bool Codecs(const std::string& key_system, base::string16* codecs);

[xhwang, 2016/01/29 07:43:07]

ditto about name too general. How about GetSupportedCodecs?

[jrummell, 2016/03/04 01:19:41]

Done.

+
+  // Return the list of all registered key systems and the path to the
+  // library. Note that multiple key systems may use the same library,
+  // so some of the entries in |paths| may be duplicated.
+  void GetAllRegisteredKeySystems(std::vector<std::string>* key_systems,
+                                  std::vector<base::FilePath>* paths);

[xhwang, 2016/01/29 07:43:07]

What's the purpose of this API? It's a bit odd that we return |key_systems| and
|paths| separately.

[jrummell, 2016/03/04 01:19:41]

Combined using std::pair.

+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<KeySystemService>;
+
+  KeySystemService();
+  ~KeySystemService();
+
+  std::vector<KeySystemRegistration> registered_key_systems_;
+
+  DISALLOW_COPY_AND_ASSIGN(KeySystemService);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_COMMON_KEY_SYSTEM_SERVICE_H_