Fixes audio issue on Mac for USB headsets

media/audio/mac/audio_low_latency_input_mac.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/audio/mac/audio_low_latency_input_mac.h"
 
 #include <CoreServices/CoreServices.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
@@ skipping 478 matching lines @@
   // Receive audio from the AUHAL from the output scope of the Audio Unit.
   OSStatus result = AudioUnitRender(audio_input->audio_unit(),
                                     flags,
                                     time_stamp,
                                     bus_number,
                                     number_of_frames,
                                     audio_input->audio_buffer_list());
   if (result) {
     UMA_HISTOGRAM_SPARSE_SLOWLY("Media.AudioInputCbErrorMac", result);
     OSSTATUS_DLOG(ERROR, result) << "AudioUnitRender() failed ";
-    audio_input->HandleError(result);
+    if (result != kAudioUnitErr_TooManyFramesToProcess) {
+      // We avoid stopping the stream for kAudioUnitErr_TooManyFramesToProcess
+      // since it has been observed that some USB headsets can cause this error
+      // but only for a few initial frames at startup and then then the stream

[DaleCurtis, 2015/03/18 22:09:06]

Since you explicitly mention that this returns to normal shortly, can you add a
backoff count which fires an error once a threshold is hit?

[no longer working on chromium, 2015/03/18 22:15:01]

It is a bit hard to define the threshold since it depends on the device, sort of
timing things related to ramp change.

How about adding a uma stat to get some understanding?

+      // returns to a stable state again.
+      // See b/19524368 for details.
+      audio_input->HandleError(result);
+    }
     return result;
   }
 
   // Deliver recorded data to the consumer as a callback.
   return audio_input->Provide(number_of_frames,
                               audio_input->audio_buffer_list(),
                               time_stamp);
 }
 
 OSStatus AUAudioInputStream::Provide(UInt32 number_of_frames,
@@ skipping 176 matching lines @@
     kAudioDevicePropertyScopeInput,
     static_cast<UInt32>(channel)
   };
   OSStatus result = AudioObjectIsPropertySettable(input_device_id_,
                                                   &property_address,
                                                   &is_settable);
   return (result == noErr) ? is_settable : false;
 }
 
 }  // namespace media