Instrument parser blocking script execution time.

third_party/WebKit/Source/core/dom/ScriptLoader.h

 /*
  * Copyright (C) 2008 Nikolas Zimmermann <zimmermann@kde.org>
  *
  * 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef ScriptLoader_h
 #define ScriptLoader_h
 
 #include "core/CoreExport.h"
 #include "core/dom/PendingScript.h"
+#include "core/dom/ScriptRunner.h"
 #include "core/fetch/FetchRequest.h"
 #include "core/fetch/ResourceClient.h"
 #include "core/fetch/ScriptResource.h"
+#include "wtf/Optional.h"
 #include "wtf/text/TextPosition.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class Element;
 class ScriptLoaderClient;
 class ScriptSourceCode;
 class LocalFrame;
 
@@ skipping 51 matching lines @@
 
 protected:
     ScriptLoader(Element*, bool createdByParser, bool isEvaluated, bool createdDuringDocumentWrite);
 
 private:
     bool ignoresLoadRequest() const;
     bool isScriptForEventSupported() const;
     void logScriptMimetype(ScriptResource*, LocalFrame*, String);
 
     bool fetchScript(const String& sourceUrl, FetchRequest::DeferOption);
+    bool doExecuteScript(const ScriptSourceCode&);
 
     ScriptLoaderClient* client() const;
 
     // ResourceClient
     void notifyFinished(Resource*) override;
     String debugName() const override { return "ScriptLoader"; }
 
     Member<Element> m_element;
     Member<ScriptResource> m_resource;
     WTF::OrdinalNumber m_startLineNumber;
     String m_characterEncoding;
     String m_fallbackCharacterEncoding;
 
     bool m_parserInserted : 1;
     bool m_isExternalScript : 1;
     bool m_alreadyStarted : 1;
     bool m_haveFiredLoad : 1;
     bool m_willBeParserExecuted : 1; // Same as "The parser will handle executing the script."
     bool m_readyToBeParserExecuted : 1;
-    bool m_willExecuteInOrder : 1;
     bool m_willExecuteWhenDocumentFinishedParsing : 1;
     bool m_forceAsync : 1;
     const bool m_createdDuringDocumentWrite : 1;
 
+    // Async scripts may either execute as their load completes, or 'in
+    // order'. See http://www.html5rocks.com/en/tutorials/speed/script-loading/
+    // for more information.
+    WTF::Optional<ScriptRunner::ExecutionType> m_asyncExecType;

[kouhei (in TOK), 2016/08/26 10:01:48]

Would you add another ExecutionType instead of WTF::Optional?

[Bryan McQuade, 2016/08/28 21:09:23]

Sure. I also renamed the enum to AsyncExecutionType, since it's specific to
async scripts, and fixed the enum naming to match the blink style guide
(AsyncExecution rather than ASYNC_EXECUTION). PTAL, thanks!

+
     Member<PendingScript> m_pendingScript;
 };
 
 ScriptLoader* toScriptLoaderIfPossible(Element*);
 
 } // namespace blink
 
 #endif // ScriptLoader_h