Fix crash with MIDI send for MidiManagerAlsa

media/midi/midi_manager.cc

Index: media/midi/midi_manager.cc
diff --git a/media/midi/midi_manager.cc b/media/midi/midi_manager.cc
index be2a1d526a0e229f8204e3fecc234ba956dd5717..5fe9f2139f0ff3d325b53a3478cec4b3caad3488 100644
--- a/media/midi/midi_manager.cc
+++ b/media/midi/midi_manager.cc
@@ -149,11 +149,10 @@ void MidiManager::EndSession(MidiManagerClient* client) {
 }
 
 void MidiManager::AccumulateMidiBytesSent(MidiManagerClient* client, size_t n) {
-  {
-    base::AutoLock auto_lock(lock_);
-    if (clients_.find(client) == clients_.end())
-      return;
-  }
+  base::AutoLock auto_lock(lock_);
+  if (clients_.find(client) == clients_.end())
+    return;
+
   client->AccumulateMidiBytesSent(n);

[Takashi Toyoshima, 2015/12/07 06:00:28]

Good catch.

Can you add a comment here?

We are likely to unlock any mutex before calling a callback as possible. Without
any comment, someone may be revert this fix unexpectedly to avoid a potential
deadlock.

 }