Improves stereo/mono audio support on Android

webrtc/modules/audio_device/android/opensles_recorder.cc

Index: webrtc/modules/audio_device/android/opensles_recorder.cc
diff --git a/webrtc/modules/audio_device/android/opensles_recorder.cc b/webrtc/modules/audio_device/android/opensles_recorder.cc
index e3a6e61ab024658700c1cb632fba993333fc1da8..df94ba8e156f64a5b68fe7d608247ca9c4013192 100644
--- a/webrtc/modules/audio_device/android/opensles_recorder.cc
+++ b/webrtc/modules/audio_device/android/opensles_recorder.cc
@@ -76,6 +76,11 @@ OpenSLESRecorder::~OpenSLESRecorder() {
 int OpenSLESRecorder::Init() {
   ALOGD("Init%s", GetThreadInfo().c_str());
   RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  if (audio_parameters_.channels() == 2) {
+    // TODO(henrika): FineAudioBuffer needs more work to support stereo.
+    ALOGE("OpenSLESRecorder does not support stereo");
+    return -1;
+  }
   return 0;
 }