Make OS audio buffer size limits visible.

media/base/audio_latency.cc

Index: media/base/audio_latency.cc
diff --git a/media/base/audio_latency.cc b/media/base/audio_latency.cc
index 61b3724efa48cc36fc8ff7c3a545c95d7ba5bb56..05c9ac4ad18f883d4ec012f9a51fc2bd45bd2c09 100644
--- a/media/base/audio_latency.cc
+++ b/media/base/audio_latency.cc
@@ -11,6 +11,7 @@
 #include "base/logging.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
+#include "media/base/limits.h"
 
 namespace media {
 
@@ -132,6 +133,12 @@ int AudioLatency::GetExactBufferSize(base::TimeDelta duration,
                                      int hardware_buffer_size) {
   const double requested_buffer_size = duration.InSecondsF() * sample_rate;
 
+  // On OSX the preferred buffer size is larger than the minimum, however we
+  // allow values down to the minimum if requested explicitly.
+#if defined(OS_MACOSX)
+  hardware_buffer_size = limits::kMinimumOutputBufferSize;
+#endif
+
   DCHECK_NE(0, hardware_buffer_size);
 
   // Round the requested size to the nearest multiple of the hardware size
@@ -139,7 +146,8 @@ int AudioLatency::GetExactBufferSize(base::TimeDelta duration,
       std::round(std::max(requested_buffer_size, 1.0) / hardware_buffer_size) *
       hardware_buffer_size;
 
-  return std::max(buffer_size, hardware_buffer_size);
+  return std::min(static_cast<int>(media::limits::kMaximumOutputBufferSize),
+                  std::max(buffer_size, hardware_buffer_size));
 }
 
 }  // namespace media