Add CDM FileIO tests.

media/cdm/ppapi/cdm_adapter.cc

Index: media/cdm/ppapi/cdm_adapter.cc
diff --git a/media/cdm/ppapi/cdm_adapter.cc b/media/cdm/ppapi/cdm_adapter.cc
index 209335bdd3fc1ce07bc8d4a223f09a7f5b5969a3..cbb183e349e6a048c90e29a0ca2687ca4faa0835 100644
--- a/media/cdm/ppapi/cdm_adapter.cc
+++ b/media/cdm/ppapi/cdm_adapter.cc
@@ -4,6 +4,7 @@
 
 #include "media/cdm/ppapi/cdm_adapter.h"
 
+#include "media/cdm/ppapi/cdm_file_io_impl.h"
 #include "media/cdm/ppapi/cdm_helpers.h"
 #include "media/cdm/ppapi/supported_cdm_versions.h"
 
@@ -894,6 +895,11 @@ void CdmAdapter::OnDeferredInitializationDone(cdm::StreamType stream_type,
   }
 }
 
+// The CDM owns the returned object and must call FileIO::Close() to release it.
+cdm::FileIO* CdmAdapter::CreateFileIO(cdm::FileIOClient* client) {
+  return new CdmFileIOImpl(client, pp_instance());
+}
+
 #if defined(OS_CHROMEOS)
 void CdmAdapter::SendPlatformChallengeDone(int32_t result) {
   challenge_in_progress_ = false;