Add metrics for style update time before FCP.

third_party/WebKit/Source/core/css/StyleSheetContents.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2012 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 310 matching lines @@
 const AtomicString& StyleSheetContents::namespaceURIFromPrefix(
     const AtomicString& prefix) {
   return m_namespaces.get(prefix);
 }
 
 void StyleSheetContents::parseAuthorStyleSheet(
     const CSSStyleSheetResource* cachedStyleSheet,
     const SecurityOrigin* securityOrigin) {
   TRACE_EVENT1("blink,devtools.timeline", "ParseAuthorStyleSheet", "data",
                InspectorParseAuthorStyleSheetEvent::data(cachedStyleSheet));
-  double startTimeMS = monotonicallyIncreasingTimeMS();
+  double startTime = monotonicallyIncreasingTime();
 
   bool isSameOriginRequest =
       securityOrigin && securityOrigin->canRequest(baseURL());
 
   // When the response was fetched via the Service Worker, the original URL may
   // not be same as the base URL.
   // TODO(horo): When we will use the original URL as the base URL, we can
   // remove this check. crbug.com/553535
   if (cachedStyleSheet->response().wasFetchedViaServiceWorker()) {
     const KURL originalURL(
@@ skipping 15 matching lines @@
     // Try to get deprecated header.
     m_sourceMapURL = response.httpHeaderField(HTTPNames::X_SourceMap);
   }
 
   CSSParserContext context(parserContext(), UseCounter::getFrom(this));
   CSSParser::parseSheet(context, this, sheetText,
                         RuntimeEnabledFeatures::lazyParseCSSEnabled());
 
   DEFINE_STATIC_LOCAL(CustomCountHistogram, parseHistogram,
                       ("Style.AuthorStyleSheet.ParseTime", 0, 10000000, 50));
-  double parseDurationMS = (monotonicallyIncreasingTimeMS() - startTimeMS);
-  parseHistogram.count(parseDurationMS * 1000);
+  double parseDurationSeconds = (monotonicallyIncreasingTime() - startTime);
+  parseHistogram.count(parseDurationSeconds * 1000 * 1000);
   if (Document* document = singleOwnerDocument()) {
-    // CSSTiming expects time in seconds.
-    CSSTiming::from(*document).recordAuthorStyleSheetParseTime(parseDurationMS /
-                                                               1000);
+    CSSTiming::from(*document).recordAuthorStyleSheetParseTime(
+        parseDurationSeconds);
   }
 }
 
 void StyleSheetContents::parseString(const String& sheetText) {
   parseStringAtPosition(sheetText, TextPosition::minimumPosition());
 }
 
 void StyleSheetContents::parseStringAtPosition(
     const String& sheetText,
     const TextPosition& startPosition) {
@@ skipping 302 matching lines @@
   visitor->trace(m_importRules);
   visitor->trace(m_namespaceRules);
   visitor->trace(m_childRules);
   visitor->trace(m_loadingClients);
   visitor->trace(m_completedClients);
   visitor->trace(m_ruleSet);
   visitor->trace(m_referencedFromResource);
 }
 
 }  // namespace blink