Add Decryptor interface.

media/base/decryptor.h

+// Copyright (c) 2012 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 MEDIA_BASE_DECRYPTOR_H_
+#define MEDIA_BASE_DECRYPTOR_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+class DecoderBuffer;
+
+// Performs key operations and decrypts encrypted buffer.
+// All public methods other than Decrypt() will be called on the renderer
+// thread. Therefore, these calls should be fast and nonblocking, with key
+// events fired asynchronously. Decrypt() will be called on the (video/audio)
+// decoder thread synchronously.
+class MEDIA_EXPORT Decryptor {
+ public:
+  enum KeyError {
+    kUnknownError = 1,
+    kClientError,
+    kServiceError,
+    kOutputError,
+    kHardwareChangeError,
+    kDomainError
+  };
+
+  Decryptor();

[scherkus (not reviewing), 2012/06/19 16:46:00]

nit: since this is a pure virtual class you can inline the ctor + dtor and
delete the .cc file

[xhwang, 2012/06/19 16:54:57]

Done.

+  virtual ~Decryptor();
+
+  // Generates a key request for the |key_system| with |init_data| provided.
+  virtual void GenerateKeyRequest(const std::string& key_system,
+                                  const uint8* init_data,
+                                  int init_data_length) = 0;
+
+  // Adds a |key| to the |key_system|. The |key| is not limited to a decryption
+  // key. It can be any data that the key system accepts, such as a license.
+  // If multiple calls of this function set different keys for the same
+  // key ID, the older key will be replaced by the newer key.
+  virtual void AddKey(const std::string& key_system,
+                      const uint8* key,
+                      int key_length,
+                      const uint8* init_data,
+                      int init_data_length,
+                      const std::string& session_id) = 0;
+
+  // Cancels the key request specified by |session_id|.
+  virtual void CancelKeyRequest(const std::string& key_system,
+                                const std::string& session_id) = 0;
+
+  // Decrypts the |input| buffer, which should not be NULL.
+  // Returns a DecoderBuffer with the decrypted data if decryption succeeded.
+  // Returns NULL if decryption failed.
+  virtual scoped_refptr<DecoderBuffer> Decrypt(
+      const scoped_refptr<DecoderBuffer>& input) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(Decryptor);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_DECRYPTOR_H_