Support sample rates up to 384 kHz.

third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp

Index: third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp b/third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp
index 0a5699da99a0a795ead0eb89edbf14531c76573d..9c1d943302730e0795005750650a08a98ad2c249 100644
--- a/third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp
@@ -106,7 +106,7 @@ OfflineAudioContext* OfflineAudioContext::create(ExecutionContext* context, unsi
     // AudioUtilities::maxAudioBufferSampleRate().  The number of buckets is
     // fairly arbitrary.
     DEFINE_STATIC_LOCAL(CustomCountHistogram, offlineContextSampleRateHistogram,
-        ("WebAudio.OfflineAudioContext.SampleRate", 3000, 192000, 50));
+        ("WebAudio.OfflineAudioContext.SampleRate", 3000, 384000, 50));

[Mark P, 2016/09/13 19:06:39]

Widening the histogram like this is messy because all the buckets will shift. 
(The 50 buckets are spread exponentially between the min and maximum values, and
you're changing the maximum values.)  Technically this is okay -- entries are
emitted to the histogram under the same conditions as before -- but the
dashboard will display a mess because different buckets will overlap.

I suggest changing the name of the histogram.  (This means marking the old
histogram as obsolete and adding a new one with the same description.)

If data continuity is important to you, you can also keep emits to the old
histogram name and delete the old histogram after a while.  I.e., have two
overlapping histograms emitted for some time.

[Raymond Toy, 2016/09/13 20:12:28]

Yeah, I suspected it would make a mess of the existing data.  I'll add a new
histogram for this and think about whether to keep the old one around for a bit.

Thanks!

 
     offlineContextChannelCountHistogram.sample(numberOfChannels);
     offlineContextLengthHistogram.count(numberOfFrames);