Make OS audio buffer size limits visible.

media/base/mac/audio_latency_mac.cc

Index: media/base/mac/audio_latency_mac.cc
diff --git a/media/base/mac/audio_latency_mac.cc b/media/base/mac/audio_latency_mac.cc
new file mode 100644
index 0000000000000000000000000000000000000000..223e3ad87a208c972605eb1953f307c48594712c
--- /dev/null
+++ b/media/base/mac/audio_latency_mac.cc
@@ -0,0 +1,23 @@
+// Copyright 2017 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/base/mac/audio_latency_mac.h"
+#include "media/base/limits.h"
+
+namespace media {
+
+int GetMinAudioBufferSizeMacOS(int min_buffer_size, int sample_rate) {
+  int buffer_size = min_buffer_size;
+  if (sample_rate > 48000) {
+    // The default buffer size is too small for higher sample rates and may lead
+    // to glitching.  Adjust upwards by multiples of the default size.
+    if (sample_rate <= 96000)
+      buffer_size = 2 * limits::kMinAudioBufferSize;
+    else if (sample_rate <= 192000)
+      buffer_size = 4 * limits::kMinAudioBufferSize;
+  }
+  return buffer_size;
+}
+
+}  // namespace media