Remove EventSender from HTMLLinkElement

This CL replaces EventSender in HTMLLinkElement with postTask():
Instead of calling HTMLLinkElement::dispatchPendingLoadEvents() in
Document::implicitClose() to enforce <link>'s onload events to be executed
before the document's onload event, this CL blocks document's onload until
<link>'s onload event using IncrementLoadEventDelayCount.

This CL also modifies SimTest:
This CL potentially makes onload events of <link> and documents async and
delayed, and thus SimTest can be destructed before document's onload event,
which cause assertion failure.
This CL calls testing::runPendingTasks() in ~SimTest() to flush scheduled
onload events to make Document to be loaded before SimTest's destruction.

BUG=624697

Review-Url: https://codereview.chromium.org/2275493002
Cr-Commit-Position: refs/heads/master@{#418835}

third_party/WebKit/Source/core/dom/Document.cpp

@@ -2642,7 +2642,6 @@ void Document::implicitClose()
         ImageLoader::dispatchPendingLoadEvents();
         ImageLoader::dispatchPendingErrorEvents();
 
-        HTMLLinkElement::dispatchPendingLoadEvents();
         HTMLStyleElement::dispatchPendingLoadEvents();
     }
 

third_party/WebKit/Source/core/html/HTMLLinkElement.cpp

@@ -33,8 +33,8 @@
 #include "core/dom/Attribute.h"
 #include "core/dom/Document.h"
 #include "core/dom/StyleEngine.h"
+#include "core/dom/TaskRunnerHelper.h"
 #include "core/events/Event.h"
-#include "core/events/EventSender.h"
 #include "core/fetch/CSSStyleSheetResource.h"
 #include "core/fetch/FetchRequest.h"
 #include "core/fetch/ResourceFetcher.h"
@@ -64,12 +64,6 @@ namespace blink {
 
 using namespace HTMLNames;
 
-static LinkEventSender& linkLoadEventSender()
-{
-    DEFINE_STATIC_LOCAL(LinkEventSender, sharedLoadEventSender, (LinkEventSender::create(EventTypeNames::load)));
-    return sharedLoadEventSender;
-}
-
 static bool styleSheetTypeIsSupported(const String& type)
 {
     String trimmedType = ContentType(type).type();
@@ -308,14 +302,8 @@ void HTMLLinkElement::notifyLoadedSheetAndAllCriticalSubresources(LoadedSheetErr
     linkStyle()->notifyLoadedSheetAndAllCriticalSubresources(errorStatus);
 }
 
-void HTMLLinkElement::dispatchPendingLoadEvents()
-{
-    linkLoadEventSender().dispatchPendingEvents();
-}
-
-void HTMLLinkElement::dispatchPendingEvent(LinkEventSender* eventSender)
+void HTMLLinkElement::dispatchPendingEvent(std::unique_ptr<IncrementLoadEventDelayCount>)
 {
-    DCHECK_EQ(eventSender, &linkLoadEventSender());
     DCHECK(m_link);
     if (m_link->hasLoaded())
         linkLoaded();
@@ -325,7 +313,7 @@ void HTMLLinkElement::dispatchPendingEvent(LinkEventSender* eventSender)
 
 void HTMLLinkElement::scheduleEvent()
 {
-    linkLoadEventSender().dispatchEventSoon(this);
+    TaskRunnerHelper::get(TaskType::DOMManipulation, &document())->postTask(BLINK_FROM_HERE, WTF::bind(&HTMLLinkElement::dispatchPendingEvent, wrapPersistent(this), passed(IncrementLoadEventDelayCount::create(document()))));
 }
 
 void HTMLLinkElement::startLoadingDynamicSheet()

third_party/WebKit/Source/core/html/HTMLLinkElement.h

@@ -28,6 +28,7 @@
 #include "core/css/CSSStyleSheet.h"
 #include "core/dom/DOMTokenList.h"
 #include "core/dom/IconURL.h"
+#include "core/dom/IncrementLoadEventDelayCount.h"
 #include "core/dom/StyleEngineContext.h"
 #include "core/fetch/ResourceOwner.h"
 #include "core/fetch/StyleSheetResource.h"
@@ -38,6 +39,7 @@
 #include "core/html/RelList.h"
 #include "core/loader/LinkLoader.h"
 #include "core/loader/LinkLoaderClient.h"
+#include <memory>
 
 namespace blink {
 
@@ -45,9 +47,6 @@ class HTMLLinkElement;
 class KURL;
 class LinkImport;
 
-template<typename T> class EventSender;
-using LinkEventSender = EventSender<HTMLLinkElement>;
-
 //
 // LinkStyle handles dynamically change-able link resources, which is
 // typically @rel="stylesheet".
@@ -166,10 +165,8 @@ public:
 
     DOMTokenList* sizes() const;
 
-    void dispatchPendingEvent(LinkEventSender*);
+    void dispatchPendingEvent(std::unique_ptr<IncrementLoadEventDelayCount>);
     void scheduleEvent();
-    void dispatchEventImmediately();
-    static void dispatchPendingLoadEvents();
 
     // From LinkLoaderClient
     bool shouldLoadLink() override;

third_party/WebKit/Source/web/tests/sim/SimTest.cpp

@@ -7,6 +7,7 @@
 #include "core/dom/Document.h"
 #include "platform/LayoutTestSupport.h"
 #include "platform/scroll/ScrollbarTheme.h"
+#include "platform/testing/UnitTestHelpers.h"
 #include "public/platform/WebSecurityOrigin.h"
 #include "public/web/WebCache.h"
 #include "web/WebLocalFrameImpl.h"
@@ -32,6 +33,9 @@ SimTest::SimTest()
 
 SimTest::~SimTest()
 {
+    // Pump the message loop to process the load event.
+    testing::runPendingTasks();
+
     Document::setThreadedParsingEnabledForTesting(true);
     LayoutTestSupport::setMockThemeEnabledForTest(false);
     ScrollbarTheme::setMockScrollbarsEnabled(false);