Remove calls to deprecated MessageLoop methods in media.

media/cdm/cdm_adapter_unittest.cc

Index: media/cdm/cdm_adapter_unittest.cc
diff --git a/media/cdm/cdm_adapter_unittest.cc b/media/cdm/cdm_adapter_unittest.cc
index 48a6dfbfb3ba67de02f30956b4e41e01985566dd..554ba303cd546af5f8be522db18d4673e0b1aa76 100644
--- a/media/cdm/cdm_adapter_unittest.cc
+++ b/media/cdm/cdm_adapter_unittest.cc
@@ -204,7 +204,7 @@ class CdmAdapterTest : public testing::Test {
     return promise;
   }
 
-  void RunUntilIdle() { message_loop_.RunUntilIdle(); }
+  void RunUntilIdle() { base::RunLoop().RunUntilIdle(); }
 
   std::unique_ptr<CdmFileIO> CreateCdmFileIO(cdm::FileIOClient* client) {
     ADD_FAILURE() << "Should never be called";