Added trace events for blink feature usage

third_party/WebKit/Source/core/frame/UseCounter.cpp

 /*
  * Copyright (C) 2012 Google, Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 18 matching lines @@
 #include "core/css/StyleSheetContents.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
 #include "core/frame/Deprecation.h"
 #include "core/frame/FrameConsole.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/LocalFrame.h"
 #include "core/inspector/ConsoleMessage.h"
 #include "core/workers/WorkerGlobalScope.h"
 #include "platform/Histogram.h"
+#include "platform/TraceEvent.h"
 
 namespace blink {
 
 static int totalPagesMeasuredCSSSampleId() { return 1; }
 
 int UseCounter::mapCSSPropertyIdToCSSSampleIdForHistogram(int id)
 {
     CSSPropertyID cssPropertyID = static_cast<CSSPropertyID>(id);
 
     switch (cssPropertyID) {
@@ skipping 543 matching lines @@
 void UseCounter::muteForInspector()
 {
     m_muteCount++;
 }
 
 void UseCounter::unmuteForInspector()
 {
     m_muteCount--;
 }
 
+void UseCounter::recordMeasurement(Feature feature)
+{
+    if (m_muteCount)
+        return;
+
+    if (!m_countBits.hasRecordedMeasurement(feature)) {
+        TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("blink.feature_usage"), "FeatureFirstUsed", "feature", feature);
+    }
+    m_countBits.recordMeasurement(feature);
+}
+
 UseCounter::UseCounter()
     : m_muteCount(0)
 {
     m_CSSFeatureBits.ensureSize(lastUnresolvedCSSProperty + 1);
     m_CSSFeatureBits.clearAll();
 }
 
 UseCounter::~UseCounter()
 {
     // We always log PageDestruction so that we have a scale for the rest of the features.
@@ skipping 43 matching lines @@
 }
 
 void UseCounter::count(const Frame* frame, Feature feature)
 {
     if (!frame)
         return;
     FrameHost* host = frame->host();
     if (!host)
         return;
 
-    ASSERT(Deprecation::deprecationMessage(feature).isEmpty());
-    host->useCounter().recordMeasurement(feature);
+    host->useCounter().count(feature);
 }
 
 void UseCounter::count(const Document& document, Feature feature)
 {
     count(document.frame(), feature);
 }
 
 bool UseCounter::isCounted(Document& document, Feature feature)
 {
     Frame* frame = document.frame();
@@ skipping 67 matching lines @@
 }
 
 void UseCounter::count(CSSParserMode cssParserMode, CSSPropertyID feature)
 {
     ASSERT(feature >= firstCSSProperty);
     ASSERT(feature <= lastUnresolvedCSSProperty);
 
     if (!isUseCounterEnabledForMode(cssParserMode) || m_muteCount)
         return;
 
+    if (!m_CSSFeatureBits.quickGet(feature)) {
+        TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("blink.feature_usage"), "CSSFeatureFirstUsed", "feature", feature);
+    }
     m_CSSFeatureBits.quickSet(feature);
 }
 
 void UseCounter::count(Feature feature)
 {
     ASSERT(Deprecation::deprecationMessage(feature).isEmpty());
     recordMeasurement(feature);
 }
 
 UseCounter* UseCounter::getFrom(const Document* document)
@@ skipping 13 matching lines @@
 UseCounter* UseCounter::getFrom(const StyleSheetContents* sheetContents)
 {
     // FIXME: We may want to handle stylesheets that have multiple owners
     //        https://crbug.com/242125
     if (sheetContents && sheetContents->hasSingleOwnerNode())
         return getFrom(sheetContents->singleOwnerDocument());
     return 0;
 }
 
 } // namespace blink