media/midi: Fix warnings found by clang chromium-style plugin on Windows.

media/midi/midi_manager_win.cc

Index: media/midi/midi_manager_win.cc
diff --git a/media/midi/midi_manager_win.cc b/media/midi/midi_manager_win.cc
index a911ff6d5f371dcc93c4a4bda5ad357bdc566af5..593727864494e55f6ac7256244109be765c4073b 100644
--- a/media/midi/midi_manager_win.cc
+++ b/media/midi/midi_manager_win.cc
@@ -1093,6 +1093,13 @@ class MidiServiceWinImpl : public MidiServiceWin,
 
 }  // namespace
 
+MidiManagerWin::MidiManagerWin() {
+}
+
+MidiManagerWin::~MidiManagerWin() {
+  midi_service_.reset();

[Nico, 2015/04/29 03:21:49]

Is the explicit reset() call needed at all? There's only a single member, so
omitting this line shouldn't make a difference I think.

+}
+
 void MidiManagerWin::StartInitialization() {
   midi_service_.reset(new MidiServiceWinImpl);
   // Note that |CompleteInitialization()| will be called from the callback.