Add UMA histograms for WebAudio

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

Index: third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.cpp b/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.cpp
index f534842b8b90013c45f7b1631aa74ea23f0da936..0b65664fe4a786ed0874ecbe1308ab8c7634dcab 100644
--- a/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.cpp
@@ -24,6 +24,7 @@
 
 #include "modules/webaudio/BiquadFilterNode.h"
 #include "modules/webaudio/AudioBasicProcessorHandler.h"
+#include "platform/Histogram.h"
 
 namespace blink {
 
@@ -136,6 +137,10 @@ bool BiquadFilterNode::setType(unsigned type)
     if (type > BiquadProcessor::Allpass)
         return false;
 
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, filterTypeHistogram,
+        ("WebAudio.BiquadFilter.Type", BiquadProcessor::Allpass  + 1));

[Mark P, 2016/06/03 19:52:37]

Please put something by the enum where this is declared that the enum entries
shouldn't ever be renumbered or deleted.

[Mark P, 2016/06/03 19:52:37]

nit: extra space

[Raymond Toy, 2016/06/09 19:17:10]

Done.

+    filterTypeHistogram.count(type);
+
     getBiquadProcessor()->setType(static_cast<BiquadProcessor::FilterType>(type));
     return true;
 }