media: Add log in CdmSessionAdapter

media/base/cdm_key_information.h

Index: media/base/cdm_key_information.h
diff --git a/media/base/cdm_key_information.h b/media/base/cdm_key_information.h
index 7ed8eff693e27264c72ad50c0ad1754465dd63e4..16ea225ad36c0a986f5b5f30f47782ccc12b2f3d 100644
--- a/media/base/cdm_key_information.h
+++ b/media/base/cdm_key_information.h
@@ -43,11 +43,17 @@ struct MEDIA_EXPORT CdmKeyInformation {
   CdmKeyInformation(const CdmKeyInformation& other);
   ~CdmKeyInformation();
 
+  static std::string KeyStatusToString(KeyStatus key_status);
+
   std::vector<uint8_t> key_id;
   KeyStatus status;
   uint32_t system_code;
 };
 
+// For logging use only.
+MEDIA_EXPORT std::ostream& operator<<(std::ostream& os,
+                                      const CdmKeyInformation& info);
+
 }  // namespace media
 
 #endif  // MEDIA_BASE_CDM_KEY_INFORMATION_H_