Make OS audio buffer size limits visible.

media/audio/cras/audio_manager_cras.cc

Index: media/audio/cras/audio_manager_cras.cc
diff --git a/media/audio/cras/audio_manager_cras.cc b/media/audio/cras/audio_manager_cras.cc
index 2e6d346e73bb1d47d5c343911e4bcb6417d079ac..f3beab214c5fe283ef3fa374c5d82f95de15e7e9 100644
--- a/media/audio/cras/audio_manager_cras.cc
+++ b/media/audio/cras/audio_manager_cras.cc
@@ -24,6 +24,7 @@
 #include "media/audio/cras/cras_input.h"
 #include "media/audio/cras/cras_unified.h"
 #include "media/base/channel_layout.h"
+#include "media/base/limits.h"
 #include "media/base/localized_strings.h"
 
 // cras_util.h headers pull in min/max macros...
@@ -40,10 +41,6 @@ const int kMaxOutputStreams = 50;
 // Default sample rate for input and output streams.
 const int kDefaultSampleRate = 48000;
 
-// Define bounds for the output buffer size.
-const int kMinimumOutputBufferSize = 512;
-const int kMaximumOutputBufferSize = 8192;
-
 // Default input buffer size.
 const int kDefaultInputBufferSize = 1024;
 
@@ -308,7 +305,7 @@ int AudioManagerCras::GetMinimumOutputBufferSizePerBoard() {
     return 768;
   else if (board == "samus")
     return 256;
-  return kMinimumOutputBufferSize;
+  return 512;
 }
 
 AudioParameters AudioManagerCras::GetPreferredOutputStreamParameters(
@@ -323,8 +320,9 @@ AudioParameters AudioManagerCras::GetPreferredOutputStreamParameters(
     bits_per_sample = input_params.bits_per_sample();
     channel_layout = input_params.channel_layout();
     buffer_size =
-        std::min(kMaximumOutputBufferSize,
-                 std::max(buffer_size, input_params.frames_per_buffer()));
+        std::min(static_cast<int>(limits::kMaxAudioBufferSize),
+                 std::max(static_cast<int>(limits::kMinAudioBufferSize),
+                          input_params.frames_per_buffer()));
   }
 
   int user_buffer_size = GetUserBufferSize();