Correct channel mask on android

media/audio/android/opensles_output.cc

Index: media/audio/android/opensles_output.cc
diff --git a/media/audio/android/opensles_output.cc b/media/audio/android/opensles_output.cc
index 7a4b68b3bd3d87f2a14bdb80b49e86a7ba3c14ae..3b5ee648c7f846c425ab40e9db7a30815b6fe839 100644
--- a/media/audio/android/opensles_output.cc
+++ b/media/audio/android/opensles_output.cc
@@ -26,8 +26,13 @@ OpenSLESOutputStream::OpenSLESOutputStream(AudioManagerAndroid* manager,
   format_.samplesPerSec = static_cast<SLuint32>(params.sample_rate() * 1000);
   format_.bitsPerSample = params.bits_per_sample();
   format_.containerSize = params.bits_per_sample();
-  format_.channelMask = SL_SPEAKER_FRONT_CENTER;
   format_.endianness = SL_BYTEORDER_LITTLEENDIAN;
+  if (format_.numChannels == 1)
+    format_.channelMask = SL_SPEAKER_FRONT_CENTER;
+  else if (format_.numChannels == 2)
+    format_.channelMask = SL_SPEAKER_FRONT_LEFT | SL_SPEAKER_FRONT_RIGHT;
+  else
+    NOTREACHED() << "Unsupported number of channels: " << format_.numChannels;
 
   buffer_size_bytes_ = params.GetBytesPerBuffer();