Remove custom counts histogram from the blink API.

third_party/WebKit/Source/core/html/parser/HTMLResourcePreloader.cpp

 /*
  * Copyright (C) 2013 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 11 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/html/parser/HTMLResourcePreloader.h"
 
 #include "core/dom/Document.h"
 #include "core/fetch/FetchInitiatorInfo.h"
 #include "core/fetch/ResourceFetcher.h"
 #include "core/loader/DocumentLoader.h"
+#include "platform/Histogram.h"
 #include "public/platform/Platform.h"
 
 namespace blink {
 
 inline HTMLResourcePreloader::HTMLResourcePreloader(Document& document)
     : m_document(document)
 {
 }
 
 PassOwnPtrWillBeRawPtr<HTMLResourcePreloader> HTMLResourcePreloader::create(Document& document)
@@ skipping 26 matching lines @@
     if (!m_document->loader())
         return;
     FetchRequest request = preload->resourceRequest(m_document);
     // TODO(dgozman): This check should go to HTMLPreloadScanner, but this requires
     // making Document::completeURLWithOverride logic to be statically accessible.
     if (request.url().protocolIsData())
         return;
     if (preload->resourceType() == Resource::Script || preload->resourceType() == Resource::CSSStyleSheet || preload->resourceType() == Resource::ImportResource)
         request.setCharset(preload->charset().isEmpty() ? m_document->characterSet().string() : preload->charset());
     request.setForPreload(true);
-    Platform::current()->histogramCustomCounts("WebCore.PreloadDelayMs", static_cast<int>(1000 * (monotonicallyIncreasingTime() - preload->discoveryTime())), 0, 2000, 20);
+    int duration = static_cast<int>(1000 * (monotonicallyIncreasingTime() - preload->discoveryTime()));
+    DEFINE_THREAD_SAFE_STATIC_LOCAL(CustomCountHistogram, preloadDelayHistogram, new CustomCountHistogram("WebCore.PreloadDelayMs", 0, 2000, 20));

[esprehn, 2016/02/04 23:25:23]

main thread only, m_document below is only accessible from the main thread

+    preloadDelayHistogram.count(duration);
     m_document->loader()->startPreload(preload->resourceType(), request);
 }
 
 } // namespace blink