Generalize AesDecryptor to make it more spec compliant.

media/crypto/aes_decryptor.h

Index: media/crypto/aes_decryptor.h
diff --git a/media/crypto/aes_decryptor.h b/media/crypto/aes_decryptor.h
index d62528f0fa73beeedf61e39596b2856e9548196c..3338e7159f6471af40a6fed48548ab5a2fe1fea0 100644
--- a/media/crypto/aes_decryptor.h
+++ b/media/crypto/aes_decryptor.h
@@ -20,23 +20,55 @@ class SymmetricKey;
 namespace media {
 
 class DecoderBuffer;
+class DecryptorClient;
 
 // Decrypts AES encrypted buffer into unencrypted 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 AesDecryptor {
  public:
-  AesDecryptor();
+  enum KeyError {
+    kUnknownError = 1,
+    kClientError,
+    kServiceError,
+    kOutputError,
+    kHardwareChangeError,
+    kDomainError
+  };
+
+  // The AesDecryptor does not take ownership of the |client|. The |client|
+  // must be valid throughout the lifetime of the AesDecryptor.
+  explicit AesDecryptor(DecryptorClient* client);
   ~AesDecryptor();
 
-  // Add a |key_id| and |key| pair 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.
-  void AddKey(const uint8* key_id, int key_id_size,
-              const uint8* key, int key_size);
+  // Generates a key request. The result of this call will be reported via the
+  // client's KeyMessage() or KeyError() methods.
+  void GenerateKeyRequest(const std::string& key_system,
+                          const uint8* init_data,
+                          int init_data_length);
+
+  // 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.
+  // The result of this call will be reported via the client's KeyAdded(),
+  // KeyMessage() or KeyError() methods.
+  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);
+
+  // Cancels the key request specified by |session_id|.
+  void CancelKeyRequest(const std::string& key_system,
+                        const std::string& session_id);
 
-  // Decrypt |input| buffer. The |input| should not be NULL.
-  // Return a DecoderBuffer with the decrypted data if decryption succeeded.
-  // Return NULL if decryption failed.
+  // Decrypts the |input| buffer, which should not be NULL.
+  // Returns a DecoderBuffer with the decrypted data if decryption succeeded.
+  // Returns NULL if decryption failed.
   scoped_refptr<DecoderBuffer> Decrypt(
       const scoped_refptr<DecoderBuffer>& input);
 
@@ -44,8 +76,18 @@ class MEDIA_EXPORT AesDecryptor {
   // KeyMap owns the crypto::SymmetricKey* and must delete them when they are
   // not needed any more.
   typedef base::hash_map<std::string, crypto::SymmetricKey*> KeyMap;
-  KeyMap key_map_;
-  base::Lock lock_;
+  // 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_|.
+  base::Lock key_map_lock_;  // Protects the |key_map_|.
+
+  DecryptorClient* client_;
+
+  // 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_t next_session_id_;
 
   DISALLOW_COPY_AND_ASSIGN(AesDecryptor);
 };