Make OS audio buffer size limits visible.

media/base/limits.h

Index: media/base/limits.h
diff --git a/media/base/limits.h b/media/base/limits.h
index f936c8bf9257a064c9aeac0229bec51a65ffcb15..e56d78fc981ee1a270151a1e8ffbc21d145d28ed 100644
--- a/media/base/limits.h
+++ b/media/base/limits.h
@@ -7,6 +7,8 @@
 #ifndef MEDIA_BASE_LIMITS_H_
 #define MEDIA_BASE_LIMITS_H_
 
+#include "build/build_config.h"
+
 namespace media {
 
 namespace limits {
@@ -58,6 +60,22 @@ enum {
   kMaxInitDataLength = 64 * 1024,         // 64 KB
   kMaxSessionResponseLength = 64 * 1024,  // 64 KB
   kMaxKeySystemLength = 256,
+
+// Minimum and maximum buffer sizes for certain audio platforms.
+#if defined(OS_MACOSX)
+  // Values taken from AudioManagerMac.

[DaleCurtis, 2017/06/27 17:25:08]

This is now the source of these values, so no need to list where they came from.

[Andrew MacPherson, 2017/06/27 17:46:49]

Done.

+  kMinAudioBufferSize = 128,
+  kMaxAudioBufferSize = 4096,
+#elif defined(USE_PULSEAUDIO)
+  // Values taken from AudioManagerPulse.
+  kMinAudioBufferSize = 512,
+  kMaxAudioBufferSize = 8192,
+#elif defined(USE_CRAS)
+  // Values taken from AudioManagerCras, though the minimum was dropped from 512
+  // to 256 to allow explicitly requesting this buffer size on any board.
+  kMinAudioBufferSize = 256,
+  kMaxAudioBufferSize = 8192,
+#endif
 };
 
 }  // namespace limits