Remove Enumeration Histograms from the Blink Platform API.

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 16 matching lines @@
 
 #include "core/css/CSSStyleSheet.h"
 #include "core/css/StyleSheetContents.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.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 "public/platform/Platform.h"
+#include "platform/Histogram.h"
 
 namespace blink {
 
 static int totalPagesMeasuredCSSSampleId() { return 1; }
 
 int UseCounter::m_muteCount = 0;
 
 // FIXME : This mapping should be autogenerated. This function should
 //         be moved to a separate file and a script run at build time
 //         to detect new values in CSSPropertyID and add them to the
@@ skipping 513 matching lines @@
         ASSERT_NOT_REACHED();
         return 0;
     }
 
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 static int maximumCSSSampleId() { return 518; }
 
+static EnumerationHistogram& featureObserverHistogram()
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, histogram, ("WebCore.FeatureObserver", UseCounter::NumberOfFeatures));

[esprehn, 2016/02/05 19:09:07]

Do we not use UseCounters on workers? I think this one might need to be thread
safe. I wonder what workers do...

[dtapuska, 2016/02/05 19:25:32]

I see Page is the only user of UseCounter. Are Page objects ever constructed on
workers?

+    return histogram;
+}
+
 void UseCounter::muteForInspector()
 {
     UseCounter::m_muteCount++;
 }
 
 void UseCounter::unmuteForInspector()
 {
     UseCounter::m_muteCount--;
 }
 
 UseCounter::UseCounter()
 {
     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.
-    Platform::current()->histogramEnumeration("WebCore.FeatureObserver", PageDestruction, NumberOfFeatures);
+    featureObserverHistogram().count(PageDestruction);
 
     updateMeasurements();
 }
 
 void UseCounter::CountBits::updateMeasurements()
 {
+    EnumerationHistogram& featureHistogram = featureObserverHistogram();
     for (unsigned i = 0; i < NumberOfFeatures; ++i) {
         if (m_bits.quickGet(i))
-            Platform::current()->histogramEnumeration("WebCore.FeatureObserver", i, NumberOfFeatures);
+            featureHistogram.count(i);
     }
     // Clearing count bits is timing sensitive.
     m_bits.clearAll();
 }
 
 void UseCounter::updateMeasurements()
 {
-    Platform::current()->histogramEnumeration("WebCore.FeatureObserver", PageVisits, NumberOfFeatures);
+    featureObserverHistogram().count(PageVisits);
     m_countBits.updateMeasurements();
 
     // FIXME: Sometimes this function is called more than once per page. The following
     //        bool guards against incrementing the page count when there are no CSS
     //        bits set. https://crbug.com/236262.
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, cssPropertiesHistogram, ("WebCore.FeatureObserver.CSSProperties", maximumCSSSampleId()));
     bool needsPagesMeasuredUpdate = false;
     for (int i = firstCSSProperty; i <= lastUnresolvedCSSProperty; ++i) {
         if (m_CSSFeatureBits.quickGet(i)) {
             int cssSampleId = mapCSSPropertyIdToCSSSampleIdForHistogram(i);
-            Platform::current()->histogramEnumeration("WebCore.FeatureObserver.CSSProperties", cssSampleId, maximumCSSSampleId());
+            cssPropertiesHistogram.count(cssSampleId);
             needsPagesMeasuredUpdate = true;
         }
     }
 
     if (needsPagesMeasuredUpdate)
-        Platform::current()->histogramEnumeration("WebCore.FeatureObserver.CSSProperties", totalPagesMeasuredCSSSampleId(), maximumCSSSampleId());
+        cssPropertiesHistogram.count(totalPagesMeasuredCSSSampleId());
 
     m_CSSFeatureBits.clearAll();
 }
 
 void UseCounter::didCommitLoad()
 {
     updateMeasurements();
 }
 
 void UseCounter::count(const Frame* frame, Feature feature)
@@ skipping 398 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