Web MIDI: Improve device change monitornig on Windows

media/midi/midi_manager_unittest.cc

Index: media/midi/midi_manager_unittest.cc
diff --git a/media/midi/midi_manager_unittest.cc b/media/midi/midi_manager_unittest.cc
index 680f9db5bd1882a9aea86863cbc89875bbfe5192..ffbcd0fdab44b7eaed6712438f3a4bb974aa168b 100644
--- a/media/midi/midi_manager_unittest.cc
+++ b/media/midi/midi_manager_unittest.cc
@@ -12,6 +12,7 @@
 #include "base/memory/scoped_vector.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "base/system_monitor/system_monitor.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace media {
@@ -245,6 +246,9 @@ TEST_F(MidiManagerTest, AbortSession) {
 }
 
 TEST_F(MidiManagerTest, CreateMidiManager) {
+  // SystemMonitor is needed on Windows.
+  base::SystemMonitor system_monitor;
+
   scoped_ptr<FakeMidiManagerClient> client;
   client.reset(new FakeMidiManagerClient);