Update ClearKey to support CDM_6

media/cdm/aes_decryptor.h

Index: media/cdm/aes_decryptor.h
diff --git a/media/cdm/aes_decryptor.h b/media/cdm/aes_decryptor.h
index 3a177701960b3ddd8c3eabbd459b085d63900fab..dc08bb32b01dc50a8e95ab80f6fc4b1e34e5fcba 100644
--- a/media/cdm/aes_decryptor.h
+++ b/media/cdm/aes_decryptor.h
@@ -67,6 +67,9 @@ class MEDIA_EXPORT AesDecryptor : public MediaKeys, public Decryptor {
   virtual void ResetDecoder(StreamType stream_type) OVERRIDE;
   virtual void DeinitializeDecoder(StreamType stream_type) OVERRIDE;
 
+  void GetUsableKeyIds(const std::string& web_session_id,
+                       scoped_ptr<KeyIdsPromise> promise);
+
  private:
   // TODO(fgalligan): Remove this and change KeyMap to use crypto::SymmetricKey
   // as there are no decryptors that are performing an integrity check.