Revert of Teach ScriptRunner how to yield and post on loading task queue...

Revert of Teach ScriptRunner how to yield and post on loading task queue (patchset #10 id:260001 of https://codereview.chromium.org/866273005/)

Reason for revert:
Looks like this was causing oilpan leaks

Original issue's description:
> Teach ScriptRunner how to yield
> 
> Previously ScriptRunner could execute an arbitrary number of scripts
> leading to janks.  Now ScriptRunner polls shouldYieldForHighPriorityWork
> before running each script.
> 
> In addition the task to execute the scripts is now posted on the
> loading task queue.
> 
> BUG=456777
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=190648

TBR=skyostil@chromium.org,marja@chromium.org,sigbjornf@opera.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=456777

Review URL: https://codereview.chromium.org/936493003

git-svn-id: svn://svn.chromium.org/blink/trunk@190661 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/core.gypi

@@ -3750,7 +3750,6 @@
             'dom/DocumentTest.cpp',
             'dom/MainThreadTaskRunnerTest.cpp',
             'dom/RangeTest.cpp',
-            'dom/ScriptRunnerTest.cpp',
             'dom/TreeScopeTest.cpp',
             'editing/CompositionUnderlineRangeFilterTest.cpp',
             'editing/FrameSelectionTest.cpp',

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

@@ -36,7 +36,7 @@ class ScriptLoaderClient;
 class ScriptSourceCode;
 
 
-class ScriptLoader : public NoBaseWillBeGarbageCollectedFinalized<ScriptLoader>, private ScriptResourceClient {
+class ScriptLoader final : public NoBaseWillBeGarbageCollectedFinalized<ScriptLoader>, private ScriptResourceClient {
 public:
     static PassOwnPtrWillBeRawPtr<ScriptLoader> create(Element* element, bool createdByParser, bool isEvaluated)
     {
@@ -54,7 +54,7 @@ public:
     String scriptCharset() const { return m_characterEncoding; }
     String scriptContent() const;
     void executeScript(const ScriptSourceCode&, double* compilationFinishTime = 0);
-    virtual void execute();
+    void execute();
 
     // XML parser calls these
     void dispatchLoadEvent();
@@ -78,15 +78,14 @@ public:
     void handleSourceAttribute(const String& sourceUrl);
     void handleAsyncAttribute();
 
-    virtual bool isReady() const { return m_pendingScript.isReady(); }
+    bool isReady() const { return m_pendingScript.isReady(); }
 
     // Clears the connection to the PendingScript (and Element and Resource).
     void detach();
 
-protected:
+private:
     ScriptLoader(Element*, bool createdByParser, bool isEvaluated);
 
-private:
     bool ignoresLoadRequest() const;
     bool isScriptForEventSupported() const;
 

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

@@ -30,14 +30,12 @@
 #include "core/dom/Element.h"
 #include "core/dom/ScriptLoader.h"
 #include "platform/heap/Handle.h"
-#include "platform/scheduler/Scheduler.h"
-#include "wtf/Functional.h"
 
 namespace blink {
 
 ScriptRunner::ScriptRunner(Document* document)
     : m_document(document)
-    , m_executeScriptsTaskFactory(WTF::bind(&ScriptRunner::executeScripts, this))
+    , m_timer(this, &ScriptRunner::timerFired)
 {
     ASSERT(document);
 }
@@ -79,13 +77,13 @@ void ScriptRunner::queueScriptForExecution(ScriptLoader* scriptLoader, Execution
 
 void ScriptRunner::suspend()
 {
-    m_executeScriptsTaskFactory.cancel();
+    m_timer.stop();
 }
 
 void ScriptRunner::resume()
 {
     if (hasPendingScripts())
-        postTaskIfOneIsNotAlreadyInFlight();
+        m_timer.startOneShot(0, FROM_HERE);
 }
 
 void ScriptRunner::notifyScriptReady(ScriptLoader* scriptLoader, ExecutionType executionType)
@@ -105,7 +103,7 @@ void ScriptRunner::notifyScriptReady(ScriptLoader* scriptLoader, ExecutionType e
         RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!m_scriptsToExecuteInOrder.isEmpty());
         break;
     }
-    postTaskIfOneIsNotAlreadyInFlight();
+    m_timer.startOneShot(0, FROM_HERE);
 }
 
 void ScriptRunner::notifyScriptLoadError(ScriptLoader* scriptLoader, ExecutionType executionType)
@@ -163,54 +161,28 @@ void ScriptRunner::movePendingAsyncScript(ScriptRunner* newRunner, ScriptLoader*
     }
 }
 
-void ScriptRunner::executeScripts()
+void ScriptRunner::timerFired(Timer<ScriptRunner>* timer)
 {
+    ASSERT_UNUSED(timer, timer == &m_timer);
+
     RefPtrWillBeRawPtr<Document> protect(m_document.get());
 
-    // New scripts are always appended to m_scriptsToExecuteSoon and m_scriptsToExecuteInOrder (never prepended)
-    // so as long as we keep track of the current totals, we can ensure the order of execution if new scripts
-    // are added while executing the current ones.
-    // NOTE a yield followed by a notifyScriptReady(... ASYNC_EXECUTION) will result in that script executing
-    // before any pre-existing ScriptsToExecuteInOrder.
-    size_t numScriptsToExecuteSoon = m_scriptsToExecuteSoon.size();
-    size_t numScriptsToExecuteInOrder = m_scriptsToExecuteInOrder.size();
-    for (size_t i = 0; i < numScriptsToExecuteSoon; i++) {
-        ASSERT(!m_scriptsToExecuteSoon.isEmpty());
-        m_scriptsToExecuteSoon.takeFirst()->execute();
-        m_document->decrementLoadEventDelayCount();
-        if (yieldForHighPriorityWork())
-            return;
-    }
+    WillBeHeapVector<RawPtrWillBeMember<ScriptLoader> > scriptLoaders;
+    scriptLoaders.swap(m_scriptsToExecuteSoon);
 
-    for (size_t i = 0; i < numScriptsToExecuteInOrder; i++) {
-        ASSERT(!m_scriptsToExecuteInOrder.isEmpty());
-        if (!m_scriptsToExecuteInOrder.first()->isReady())
-            break;
-        m_scriptsToExecuteInOrder.takeFirst()->execute();
+    size_t numInOrderScriptsToExecute = 0;
+    for (; numInOrderScriptsToExecute < m_scriptsToExecuteInOrder.size() && m_scriptsToExecuteInOrder[numInOrderScriptsToExecute]->isReady(); ++numInOrderScriptsToExecute)
+        scriptLoaders.append(m_scriptsToExecuteInOrder[numInOrderScriptsToExecute]);
+    if (numInOrderScriptsToExecute)
+        m_scriptsToExecuteInOrder.remove(0, numInOrderScriptsToExecute);
+
+    size_t size = scriptLoaders.size();
+    for (size_t i = 0; i < size; ++i) {
+        scriptLoaders[i]->execute();
         m_document->decrementLoadEventDelayCount();
-        if (yieldForHighPriorityWork())
-            return;
     }
 }
 
-bool ScriptRunner::yieldForHighPriorityWork()
-{
-    if (!Scheduler::shared()->shouldYieldForHighPriorityWork())
-        return false;
-
-    postTaskIfOneIsNotAlreadyInFlight();
-    return true;
-}
-
-void ScriptRunner::postTaskIfOneIsNotAlreadyInFlight()
-{
-    if (m_executeScriptsTaskFactory.isPending())
-        return;
-
-    // FIXME: Rename task() so that it's obvious it cancels any pending task.
-    Scheduler::shared()->postLoadingTask(FROM_HERE, m_executeScriptsTaskFactory.task());
-}
-
 void ScriptRunner::trace(Visitor* visitor)
 {
 #if ENABLE(OILPAN)

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

@@ -27,12 +27,12 @@
 #define ScriptRunner_h
 
 #include "core/fetch/ResourcePtr.h"
+#include "platform/Timer.h"
 #include "platform/heap/Handle.h"
-#include "platform/scheduler/CancellableTaskFactory.h"
-#include "wtf/Deque.h"
 #include "wtf/HashMap.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/PassOwnPtr.h"
+#include "wtf/Vector.h"
 
 namespace blink {
 
@@ -63,22 +63,18 @@ public:
 private:
     explicit ScriptRunner(Document*);
 
-    void executeScripts();
+    void timerFired(Timer<ScriptRunner>*);
 
     void addPendingAsyncScript(ScriptLoader*);
 
     void movePendingAsyncScript(ScriptRunner*, ScriptLoader*);
 
-    bool yieldForHighPriorityWork();
-
-    void postTaskIfOneIsNotAlreadyInFlight();
-
     RawPtrWillBeMember<Document> m_document;
-    WillBeHeapDeque<RawPtrWillBeMember<ScriptLoader>> m_scriptsToExecuteInOrder;
+    WillBeHeapVector<RawPtrWillBeMember<ScriptLoader> > m_scriptsToExecuteInOrder;
     // http://www.whatwg.org/specs/web-apps/current-work/#set-of-scripts-that-will-execute-as-soon-as-possible
-    WillBeHeapDeque<RawPtrWillBeMember<ScriptLoader>> m_scriptsToExecuteSoon;
+    WillBeHeapVector<RawPtrWillBeMember<ScriptLoader> > m_scriptsToExecuteSoon;
     WillBeHeapHashSet<RawPtrWillBeMember<ScriptLoader> > m_pendingAsyncScripts;
-    CancellableTaskFactory m_executeScriptsTaskFactory;
+    Timer<ScriptRunner> m_timer;
 };
 
 }