Make OS audio buffer size limits visible.

third_party/WebKit/Source/platform/audio/AudioDestination.cpp

Index: third_party/WebKit/Source/platform/audio/AudioDestination.cpp
diff --git a/third_party/WebKit/Source/platform/audio/AudioDestination.cpp b/third_party/WebKit/Source/platform/audio/AudioDestination.cpp
index 39d569fd56ae9f8ab1156cca8e02ef89622fce06..1cb314629ccd716377cb69f24477cd1a19be0f1d 100644
--- a/third_party/WebKit/Source/platform/audio/AudioDestination.cpp
+++ b/third_party/WebKit/Source/platform/audio/AudioDestination.cpp
@@ -50,6 +50,12 @@ namespace blink {
 // that we would ever need. The current UMA stats indicates that this is, in
 // fact, probably too small. There are Android devices out there with a size of
 // 8000 or so.  We might need to make this larger. See: crbug.com/670747
+// TODO(andrew.macpherson): This either needs to be bigger since some OSes allow
+// buffer sizes of 8192 via latencyHint now or else we need to do some
+// validation of the latencyHint 'exact' size before passing it to
+// CreateAudioDevice. Clamping may be tricky though as the buffer size is
+// dependent on the sample rate for some platforms and we're passing in a time
+// value and not a buffer size in the latencyHint.

[hongchan, 2017/06/15 16:22:03]

Could you file a bug and add the URL in your comment above?

[Andrew MacPherson, 2017/06/19 12:36:18]

No problem, I'll take care of this when I push the next patch. Just to note that
until this is fixed though it will likely mean that it's possible to crash the
process by requesting latency that results in a buffer size of 8192 on CRAS and
Pulse.

 const size_t kFIFOSize = 8192;

[o1ka, 2017/06/15 15:33:37]

Should we set it to limits::kMaxAudioBufferSize? Or maybe
max(8192,limits::kMaxAudioBufferSize)?

[Andrew MacPherson, 2017/06/19 12:36:18]

It would need to be kMaxAudioBufferSize + AudioUtilities::kRenderQuantumFrames
but I believe that would resolve the issue. Otherwise just 8192 +
AudioUtilities::kRenderQuantumFrames, but I'll leave that up to hongchan@ and
rtoy@.

 
 std::unique_ptr<AudioDestination> AudioDestination::Create(