Make OS audio buffer size limits visible.

media/BUILD.gn

Index: media/BUILD.gn
diff --git a/media/BUILD.gn b/media/BUILD.gn
index 5436d6f3346281a698a24ac4a80ccaeb421ecf69..bd12c8a245433c582dd004b4584089745fce2d13 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -594,6 +594,13 @@ component("shared_memory_support") {
     "base/vector_math.h",
     "base/vector_math_testing.h",
   ]
+  if (is_mac) {
+    # These need to be included here because audio_latency.cc depends on them.
+    sources += [
+      "base/mac/audio_latency_mac.cc",
+      "base/mac/audio_latency_mac.h",
+    ]
+  }
   configs += [
     ":media_config",
     ":media_implementation",