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diff --git a/media/cdm/aes_decryptor.h b/media/cdm/aes_decryptor.h
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+++ b/media/cdm/aes_decryptor.h
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+// Copyright 2013 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_CRYPTO_AES_DECRYPTOR_H_
+#define MEDIA_CRYPTO_AES_DECRYPTOR_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/containers/hash_tables.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/string_piece.h"
+#include "base/synchronization/lock.h"
+#include "media/base/decryptor.h"
+#include "media/base/media_export.h"
+#include "media/base/media_keys.h"
+
+namespace crypto {
+class SymmetricKey;
+}
+
+namespace media {
+
+// Decrypts an AES encrypted buffer into an unencrypted buffer. The AES
+// encryption must be CTR with a key size of 128bits.
+class MEDIA_EXPORT AesDecryptor : public MediaKeys, public Decryptor {
+ public:
+  AesDecryptor(const KeyAddedCB& key_added_cb,
+               const KeyErrorCB& key_error_cb,
+               const KeyMessageCB& key_message_cb);
+  virtual ~AesDecryptor();
+
+  // MediaKeys implementation.
+  virtual bool GenerateKeyRequest(const std::string& type,
+                                  const uint8* init_data,
+                                  int init_data_length) OVERRIDE;
+  virtual void AddKey(const uint8* key, int key_length,
+                      const uint8* init_data, int init_data_length,
+                      const std::string& session_id) OVERRIDE;
+  virtual void CancelKeyRequest(const std::string& session_id) OVERRIDE;
+  virtual Decryptor* GetDecryptor() OVERRIDE;
+
+  // Decryptor implementation.
+  virtual void RegisterNewKeyCB(StreamType stream_type,
+                                const NewKeyCB& key_added_cb) OVERRIDE;
+  virtual void Decrypt(StreamType stream_type,
+                       const scoped_refptr<DecoderBuffer>& encrypted,
+                       const DecryptCB& decrypt_cb) OVERRIDE;
+  virtual void CancelDecrypt(StreamType stream_type) OVERRIDE;
+  virtual void InitializeAudioDecoder(const AudioDecoderConfig& config,
+                                      const DecoderInitCB& init_cb) OVERRIDE;
+  virtual void InitializeVideoDecoder(const VideoDecoderConfig& config,
+                                      const DecoderInitCB& init_cb) OVERRIDE;
+  virtual void DecryptAndDecodeAudio(
+      const scoped_refptr<DecoderBuffer>& encrypted,
+      const AudioDecodeCB& audio_decode_cb) OVERRIDE;
+  virtual void DecryptAndDecodeVideo(
+      const scoped_refptr<DecoderBuffer>& encrypted,
+      const VideoDecodeCB& video_decode_cb) OVERRIDE;
+  virtual void ResetDecoder(StreamType stream_type) OVERRIDE;
+  virtual void DeinitializeDecoder(StreamType stream_type) OVERRIDE;
+
+ private:
+  // TODO(fgalligan): Remove this and change KeyMap to use crypto::SymmetricKey
+  // as there are no decryptors that are performing an integrity check.
+  // Helper class that manages the decryption key.
+  class DecryptionKey {
+   public:
+    explicit DecryptionKey(const std::string& secret);
+    ~DecryptionKey();
+
+    // Creates the encryption key.
+    bool Init();
+
+    crypto::SymmetricKey* decryption_key() { return decryption_key_.get(); }
+
+   private:
+    // The base secret that is used to create the decryption key.
+    const std::string secret_;
+
+    // The key used to decrypt the data.
+    scoped_ptr<crypto::SymmetricKey> decryption_key_;
+
+    DISALLOW_COPY_AND_ASSIGN(DecryptionKey);
+  };
+
+  // Sets |key| for |key_id|. The AesDecryptor takes the ownership of the |key|.
+  void SetKey(const std::string& key_id, scoped_ptr<DecryptionKey> key);
+
+  // Gets a DecryptionKey associated with |key_id|. The AesDecryptor still owns
+  // the key. Returns NULL if no key is associated with |key_id|.
+  DecryptionKey* GetKey(const std::string& key_id) const;
+
+  // Callbacks for firing key events.
+  KeyAddedCB key_added_cb_;
+  KeyErrorCB key_error_cb_;
+  KeyMessageCB key_message_cb_;
+
+  // KeyMap owns the DecryptionKey* and must delete them when they are
+  // not needed any more.
+  typedef base::hash_map<std::string, DecryptionKey*> KeyMap;
+
+  // Since only Decrypt() is called off the renderer thread, we only need to
+  // protect |key_map_|, the only member variable that is shared between
+  // Decrypt() and other methods.
+  KeyMap key_map_;  // Protected by the |key_map_lock_|.
+  mutable base::Lock key_map_lock_;  // Protects the |key_map_|.
+
+  // Make session ID unique per renderer by making it static.
+  // TODO(xhwang): Make session ID more strictly defined if needed:
+  // https://www.w3.org/Bugs/Public/show_bug.cgi?id=16739#c0
+  static uint32 next_session_id_;
+
+  NewKeyCB new_audio_key_cb_;
+  NewKeyCB new_video_key_cb_;
+
+  DISALLOW_COPY_AND_ASSIGN(AesDecryptor);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_CRYPTO_AES_DECRYPTOR_H_