WebAudio: record whether user gesture was available and provided.

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

Index: third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.cpp b/third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.cpp
index de36a35f9e0956e38df02b948b4fc8e3c06f7948..b9082f9a3d64e14c00199d0a0ea36e4dcedf5f60 100644
--- a/third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.cpp
@@ -32,6 +32,7 @@
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContextTask.h"
+#include "core/frame/Settings.h"
 #include "core/html/HTMLMediaElement.h"
 #include "modules/mediastream/MediaStream.h"
 #include "modules/webaudio/AnalyserNode.h"
@@ -64,13 +65,27 @@
 #include "modules/webaudio/ScriptProcessorNode.h"
 #include "modules/webaudio/StereoPannerNode.h"
 #include "modules/webaudio/WaveShaperNode.h"
+#include "platform/Histogram.h"
 #include "platform/ThreadSafeFunctional.h"
+#include "platform/UserGestureIndicator.h"
 #include "platform/audio/IIRFilter.h"
 #include "public/platform/Platform.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
+namespace {
+
+enum UserGestureRecord {
+    UserGestureRequiredAndAvailable = 0,
+    UserGestureRequiredAndNotAvailable,
+    UserGestureNotRequiredAndAvailable,
+    UserGestureNotRequiredAndNotAvailable,
+    UserGestureRecordMax
+};
+
+} // anonymous namespace
+
 AbstractAudioContext* AbstractAudioContext::create(Document& document, ExceptionState& exceptionState)
 {
     return AudioContext::create(document, exceptionState);
@@ -86,6 +101,7 @@ AbstractAudioContext::AbstractAudioContext(Document* document)
     , m_destinationNode(nullptr)
     , m_isCleared(false)
     , m_isResolvingResumePromises(false)
+    , m_userGestureRequired(false)
     , m_connectionCount(0)
     , m_deferredTaskHandler(DeferredTaskHandler::create())
     , m_contextState(Suspended)
@@ -95,6 +111,12 @@ AbstractAudioContext::AbstractAudioContext(Document* document)
     , m_periodicWaveSawtooth(nullptr)
     , m_periodicWaveTriangle(nullptr)
 {
+    // TODO(mlamouri): we might want to use other ways of checking for this but
+    // in order to record metrics, re-using the HTMLMediaElement setting is
+    // probably the simplest solution.
+    if (document->settings() && document->settings()->mediaPlaybackRequiresUserGesture())
+        m_userGestureRequired = true;
+
     m_destinationNode = DefaultAudioDestinationNode::create(this);
 
     initialize();
@@ -107,6 +129,7 @@ AbstractAudioContext::AbstractAudioContext(Document* document, unsigned numberOf
     , m_destinationNode(nullptr)
     , m_isCleared(false)
     , m_isResolvingResumePromises(false)
+    , m_userGestureRequired(false)
     , m_connectionCount(0)
     , m_deferredTaskHandler(DeferredTaskHandler::create())
     , m_contextState(Suspended)
@@ -116,6 +139,11 @@ AbstractAudioContext::AbstractAudioContext(Document* document, unsigned numberOf
     , m_periodicWaveSawtooth(nullptr)
     , m_periodicWaveTriangle(nullptr)
 {
+    // TODO(mlamouri): we might want to use other ways of checking for this but
+    // in order to record metrics, re-using the HTMLMediaElement setting is
+    // probably the simplest solution.
+    if (document->settings() && document->settings()->mediaPlaybackRequiresUserGesture())
+        m_userGestureRequired = true;

[Raymond Toy, 2016/06/06 15:10:08]

I don't think this is needed or wanted for an offline context. (Yes, this method
shouldn't really be here; it's only used to construct an offline audio context.)

There is never any audio output for an offline context, so it's shouldn't
require a gesture to run one.

[mlamouri (slow - plz ping), 2016/06/06 15:14:45]

My understanding is that Safari iOS doesn't make any difference between offline
and non-offline. If we want to measure compat, we should probably keep the same
checks?

 }
 
 AbstractAudioContext::~AbstractAudioContext()
@@ -473,6 +501,25 @@ PeriodicWave* AbstractAudioContext::periodicWave(int type)
     }
 }
 
+void AbstractAudioContext::recordUserGestureState()
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, userGestureHistogram, ("WebAudio.UserGesture", UserGestureRecordMax));
+
+    if (!m_userGestureRequired) {
+        if (UserGestureIndicator::processingUserGesture())
+            userGestureHistogram.count(UserGestureNotRequiredAndAvailable);
+        else
+            userGestureHistogram.count(UserGestureNotRequiredAndNotAvailable);
+        return;
+    }
+    if (!UserGestureIndicator::processingUserGesture()) {
+        userGestureHistogram.count(UserGestureRequiredAndNotAvailable);
+        return;
+    }
+    userGestureHistogram.count(UserGestureRequiredAndAvailable);
+    m_userGestureRequired = false;
+}
+
 String AbstractAudioContext::state() const
 {
     // These strings had better match the strings for AudioContextState in AudioContext.idl.
@@ -717,6 +764,8 @@ void AbstractAudioContext::startRendering()
     ASSERT(isMainThread());
     ASSERT(m_destinationNode);
 
+    recordUserGestureState();
+
     if (m_contextState == Suspended) {
         destination()->audioDestinationHandler().startRendering();
         setContextState(Running);