Revert of Post loading tasks on the appropriate WebFrameScheduler's queue (patchset #17 id:310001 of https://codereview.chromium.org/1366883002/ )

Reason for revert:
BUG=538660

HTTP parsing use-after-free issues.

Original issue's description:
> Post loading tasks on the appropriate WebFrameScheduler's queue.
>
> Must be submitted after https://codereview.chromium.org/1340343003/
>
> BUG=510398
>
> Committed: https://crrev.com/bcc4ce71b07ea71a1056c3227c5bc381c52256fd
> Cr-Commit-Position: refs/heads/master@{#352036}

TBR=jochen@chromium.org,sandersd@chromium.org,skyostil@chromium.org,alexclarke@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=510398

Review URL: https://codereview.chromium.org/1379543003

Cr-Commit-Position: refs/heads/master@{#352062}

25 files changed, 50 insertions, 123 deletions

diff --git a/third_party/WebKit/Source/bindings/core/v8/ScriptStreamer.cpp b/third_party/WebKit/Source/bindings/core/v8/ScriptStreamer.cpp
index 7c178f9..d38e6cc 100644
--- a/third_party/WebKit/Source/bindings/core/v8/ScriptStreamer.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptStreamer.cpp
@@ -18,7 +18,6 @@
 #include "platform/ThreadSafeFunctional.h"
 #include "platform/TraceEvent.h"
 #include "public/platform/Platform.h"
-#include "public/platform/WebScheduler.h"
 #include "wtf/MainThread.h"
 #include "wtf/text/TextEncodingRegistry.h"
 
@@ -163,7 +162,7 @@ private:
 class SourceStream : public v8::ScriptCompiler::ExternalSourceStream {
     WTF_MAKE_NONCOPYABLE(SourceStream);
 public:
-    explicit SourceStream(WebTaskRunner* loadingTaskRunner)
+    SourceStream()
         : v8::ScriptCompiler::ExternalSourceStream()
         , m_cancelled(false)
         , m_finished(false)
@@ -171,7 +170,6 @@ public:
         , m_queueTailPosition(0)
         , m_bookmarkPosition(0)
         , m_lengthOfBOM(0)
-        , m_loadingTaskRunner(adoptPtr(loadingTaskRunner->clone()))
     {
     }
 
@@ -221,7 +219,7 @@ public:
         }
 
         // Inform main thread to re-queue the data.
-        m_loadingTaskRunner->postTask(
+        Platform::current()->mainThread()->taskRunner()->postTask(
             FROM_HERE, bind(&SourceStream::fetchDataFromResourceBuffer, this, 0));
     }
 
@@ -372,18 +370,16 @@ private:
     // We store this separately, to avoid having to guard all
     // m_queueLeadPosition references with a mutex.
     unsigned m_lengthOfBOM; // Used by both threads; guarded by m_mutex.
-
-    OwnPtr<WebTaskRunner> m_loadingTaskRunner;
 };
 
 size_t ScriptStreamer::kSmallScriptThreshold = 30 * 1024;
 
-void ScriptStreamer::startStreaming(PendingScript& script, PendingScript::Type scriptType, Settings* settings, ScriptState* scriptState, WebTaskRunner* loadingTaskRunner)
+void ScriptStreamer::startStreaming(PendingScript& script, PendingScript::Type scriptType, Settings* settings, ScriptState* scriptState)
 {
     // We don't yet know whether the script will really be streamed. E.g.,
     // suppressing streaming for short scripts is done later. Record only the
     // sure negative cases here.
-    bool startedStreaming = startStreamingInternal(script, scriptType, settings, scriptState, loadingTaskRunner);
+    bool startedStreaming = startStreamingInternal(script, scriptType, settings, scriptState);
     if (!startedStreaming)
         Platform::current()->histogramEnumeration(startedStreamingHistogramName(scriptType), 0, 2);
 }
@@ -425,7 +421,7 @@ void ScriptStreamer::streamingCompleteOnBackgroundThread()
 
     // notifyFinished might already be called, or it might be called in the
     // future (if the parsing finishes earlier because of a parse error).
-    m_loadingTaskRunner->postTask(FROM_HERE, threadSafeBind(&ScriptStreamer::streamingComplete, AllowCrossThreadAccess(this)));
+    Platform::current()->mainThread()->taskRunner()->postTask(FROM_HERE, threadSafeBind(&ScriptStreamer::streamingComplete, AllowCrossThreadAccess(this)));
 
     // The task might delete ScriptStreamer, so it's not safe to do anything
     // after posting it. Note that there's no way to guarantee that this
@@ -517,7 +513,7 @@ void ScriptStreamer::notifyAppendData(ScriptResource* resource)
 
         ASSERT(!m_stream);
         ASSERT(!m_source);
-        m_stream = new SourceStream(m_loadingTaskRunner.get());
+        m_stream = new SourceStream();
         // m_source takes ownership of m_stream.
         m_source = adoptPtr(new v8::ScriptCompiler::StreamedSource(m_stream, m_encoding));
 
@@ -568,7 +564,7 @@ void ScriptStreamer::notifyFinished(Resource* resource)
     notifyFinishedToClient();
 }
 
-ScriptStreamer::ScriptStreamer(ScriptResource* resource, PendingScript::Type scriptType, ScriptState* scriptState, v8::ScriptCompiler::CompileOptions compileOptions, WebTaskRunner* loadingTaskRunner)
+ScriptStreamer::ScriptStreamer(ScriptResource* resource, PendingScript::Type scriptType, ScriptState* scriptState, v8::ScriptCompiler::CompileOptions compileOptions)
     : m_resource(resource)
     , m_detached(false)
     , m_stream(0)
@@ -581,7 +577,6 @@ ScriptStreamer::ScriptStreamer(ScriptResource* resource, PendingScript::Type scr
     , m_scriptState(scriptState)
     , m_scriptType(scriptType)
     , m_encoding(v8::ScriptCompiler::StreamedSource::TWO_BYTE) // Unfortunately there's no dummy encoding value in the enum; let's use one we don't stream.
-    , m_loadingTaskRunner(adoptPtr(loadingTaskRunner->clone()))
 {
 }
 
@@ -637,7 +632,7 @@ void ScriptStreamer::notifyFinishedToClient()
         m_client->notifyFinished(m_resource);
 }
 
-bool ScriptStreamer::startStreamingInternal(PendingScript& script, PendingScript::Type scriptType, Settings* settings, ScriptState* scriptState, WebTaskRunner* loadingTaskRunner)
+bool ScriptStreamer::startStreamingInternal(PendingScript& script, PendingScript::Type scriptType, Settings* settings, ScriptState* scriptState)
 {
     ASSERT(isMainThread());
     ASSERT(scriptState->contextIsValid());
@@ -670,7 +665,7 @@ bool ScriptStreamer::startStreamingInternal(PendingScript& script, PendingScript
     // The Resource might go out of scope if the script is no longer
     // needed. This makes PendingScript notify the ScriptStreamer when it is
     // destroyed.
-    script.setStreamer(ScriptStreamer::create(resource, scriptType, scriptState, compileOption, loadingTaskRunner));
+    script.setStreamer(ScriptStreamer::create(resource, scriptType, scriptState, compileOption));
 
     return true;
 }
diff --git a/third_party/WebKit/Source/bindings/core/v8/ScriptStreamer.h b/third_party/WebKit/Source/bindings/core/v8/ScriptStreamer.h
index c002175..e3eb425 100644
--- a/third_party/WebKit/Source/bindings/core/v8/ScriptStreamer.h
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptStreamer.h
@@ -21,7 +21,6 @@ class ScriptResourceClient;
 class ScriptState;
 class Settings;
 class SourceStream;
-class WebTaskRunner;
 
 // ScriptStreamer streams incomplete script data to V8 so that it can be parsed
 // while it's loaded. PendingScript holds a reference to ScriptStreamer. At the
@@ -33,9 +32,9 @@ class WebTaskRunner;
 class CORE_EXPORT ScriptStreamer final : public RefCountedWillBeRefCountedGarbageCollected<ScriptStreamer> {
     WTF_MAKE_NONCOPYABLE(ScriptStreamer);
 public:
-    static PassRefPtrWillBeRawPtr<ScriptStreamer> create(ScriptResource* resource, PendingScript::Type scriptType, ScriptState* scriptState, v8::ScriptCompiler::CompileOptions compileOptions, WebTaskRunner* loadingTaskRunner)
+    static PassRefPtrWillBeRawPtr<ScriptStreamer> create(ScriptResource* resource, PendingScript::Type scriptType, ScriptState* scriptState, v8::ScriptCompiler::CompileOptions compileOptions)
     {
-        return adoptRefWillBeNoop(new ScriptStreamer(resource, scriptType, scriptState, compileOptions, loadingTaskRunner));
+        return adoptRefWillBeNoop(new ScriptStreamer(resource, scriptType, scriptState, compileOptions));
     }
 
     ~ScriptStreamer();
@@ -43,7 +42,7 @@ public:
 
     // Launches a task (on a background thread) which will stream the given
     // PendingScript into V8 as it loads.
-    static void startStreaming(PendingScript&, PendingScript::Type, Settings*, ScriptState*, WebTaskRunner*);
+    static void startStreaming(PendingScript&, PendingScript::Type, Settings*, ScriptState*);
 
     // Returns false if we cannot stream the given encoding.
     static bool convertEncoding(const char* encodingName, v8::ScriptCompiler::StreamedSource::Encoding*);
@@ -108,12 +107,12 @@ private:
     // streamed. Non-const for testing.
     static size_t kSmallScriptThreshold;
 
-    ScriptStreamer(ScriptResource*, PendingScript::Type, ScriptState*, v8::ScriptCompiler::CompileOptions, WebTaskRunner*);
+    ScriptStreamer(ScriptResource*, PendingScript::Type, ScriptState*, v8::ScriptCompiler::CompileOptions);
 
     void streamingComplete();
     void notifyFinishedToClient();
 
-    static bool startStreamingInternal(PendingScript&, PendingScript::Type, Settings*, ScriptState*, WebTaskRunner*);
+    static bool startStreamingInternal(PendingScript&, PendingScript::Type, Settings*, ScriptState*);
 
     // This pointer is weak. If PendingScript and its Resource are deleted
     // before ScriptStreamer, PendingScript will notify ScriptStreamer of its
@@ -150,8 +149,6 @@ private:
 
     // Encoding of the streamed script. Saved for sanity checking purposes.
     v8::ScriptCompiler::StreamedSource::Encoding m_encoding;
-
-    OwnPtr<WebTaskRunner> m_loadingTaskRunner;
 };
 
 } // namespace blink
diff --git a/third_party/WebKit/Source/bindings/core/v8/ScriptStreamerTest.cpp b/third_party/WebKit/Source/bindings/core/v8/ScriptStreamerTest.cpp
index cbfdd8c..62d9c84 100644
--- a/third_party/WebKit/Source/bindings/core/v8/ScriptStreamerTest.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptStreamerTest.cpp
@@ -18,7 +18,6 @@
 #include "platform/heap/Handle.h"
 #include "platform/testing/UnitTestHelpers.h"
 #include "public/platform/Platform.h"
-#include "public/platform/WebScheduler.h"
 
 #include <gtest/gtest.h>
 #include <v8.h>
@@ -65,8 +64,7 @@ private:
 class ScriptStreamingTest : public ::testing::Test {
 public:
     ScriptStreamingTest()
-        : m_loadingTaskRunner(Platform::current()->currentThread()->scheduler()->loadingTaskRunner())
-        , m_scope(v8::Isolate::GetCurrent())
+        : m_scope(v8::Isolate::GetCurrent())
         , m_settings(Settings::create())
         , m_resourceRequest("http://www.streaming-test.com/")
         , m_resource(new ScriptResource(m_resourceRequest, "UTF-8"))
@@ -118,7 +116,6 @@ protected:
         testing::runPendingTasks();
     }
 
-    WebTaskRunner* m_loadingTaskRunner; // NOT OWNED
     V8TestingScope m_scope;
     OwnPtr<Settings> m_settings;
     // The Resource and PendingScript where we stream from. These don't really
@@ -145,7 +142,7 @@ private:
 TEST_F(ScriptStreamingTest, CompilingStreamedScript)
 {
     // Test that we can successfully compile a streamed script.
-    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState(), m_loadingTaskRunner);
+    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState());
     TestScriptResourceClient client;
     pendingScript().watchForLoad(&client);
 
@@ -176,7 +173,7 @@ TEST_F(ScriptStreamingTest, CompilingStreamedScriptWithParseError)
     // Test that scripts with parse errors are handled properly. In those cases,
     // the V8 side typically finished before loading finishes: make sure we
     // handle it gracefully.
-    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState(), m_loadingTaskRunner);
+    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState());
     TestScriptResourceClient client;
     pendingScript().watchForLoad(&client);
     appendData("function foo() {");
@@ -208,7 +205,7 @@ TEST_F(ScriptStreamingTest, CancellingStreaming)
 {
     // Test that the upper layers (PendingScript and up) can be ramped down
     // while streaming is ongoing, and ScriptStreamer handles it gracefully.
-    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState(), m_loadingTaskRunner);
+    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState());
     TestScriptResourceClient client;
     pendingScript().watchForLoad(&client);
     appendData("function foo() {");
@@ -237,7 +234,7 @@ TEST_F(ScriptStreamingTest, SuppressingStreaming)
     // is suppressed (V8 doesn't parse while the script is loading), and the
     // upper layer (ScriptResourceClient) should get a notification when the
     // script is loaded.
-    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState(), m_loadingTaskRunner);
+    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState());
     TestScriptResourceClient client;
     pendingScript().watchForLoad(&client);
     appendData("function foo() {");
@@ -266,7 +263,7 @@ TEST_F(ScriptStreamingTest, EmptyScripts)
     // Empty scripts should also be streamed properly, that is, the upper layer
     // (ScriptResourceClient) should be notified when an empty script has been
     // loaded.
-    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState(), m_loadingTaskRunner);
+    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState());
     TestScriptResourceClient client;
     pendingScript().watchForLoad(&client);
 
@@ -287,7 +284,7 @@ TEST_F(ScriptStreamingTest, SmallScripts)
     // Small scripts shouldn't be streamed.
     ScriptStreamer::setSmallScriptThresholdForTesting(100);
 
-    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState(), m_loadingTaskRunner);
+    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState());
     TestScriptResourceClient client;
     pendingScript().watchForLoad(&client);
 
@@ -311,7 +308,7 @@ TEST_F(ScriptStreamingTest, ScriptsWithSmallFirstChunk)
     // chunk is small.
     ScriptStreamer::setSmallScriptThresholdForTesting(100);
 
-    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState(), m_loadingTaskRunner);
+    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState());
     TestScriptResourceClient client;
     pendingScript().watchForLoad(&client);
 
@@ -341,7 +338,7 @@ TEST_F(ScriptStreamingTest, EncodingChanges)
     // loading it.
     m_resource->setEncoding("windows-1252");
 
-    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState(), m_loadingTaskRunner);
+    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState());
     TestScriptResourceClient client;
     pendingScript().watchForLoad(&client);
 
@@ -370,7 +367,7 @@ TEST_F(ScriptStreamingTest, EncodingFromBOM)
     // will also affect encoding detection.
     m_resource->setEncoding("windows-1252"); // This encoding is wrong on purpose.
 
-    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState(), m_loadingTaskRunner);
+    ScriptStreamer::startStreaming(pendingScript(), PendingScript::ParsingBlocking, m_settings.get(), m_scope.scriptState());
     TestScriptResourceClient client;
     pendingScript().watchForLoad(&client);
 
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 34b8f70..f057388 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -5685,13 +5685,6 @@ bool Document::isSecureContext(String& errorMessage, const SecureContextCheck pr
     return true;
 }
 
-WebTaskRunner* Document::loadingTaskRunner() const
-{
-    if (frame())
-        return frame()->frameScheduler()->loadingTaskRunner();
-    return Platform::current()->currentThread()->scheduler()->loadingTaskRunner();
-}
-
 DEFINE_TRACE(Document)
 {
 #if ENABLE(OILPAN)
diff --git a/third_party/WebKit/Source/core/dom/Document.h b/third_party/WebKit/Source/core/dom/Document.h
index 511c567..926381d 100644
--- a/third_party/WebKit/Source/core/dom/Document.h
+++ b/third_party/WebKit/Source/core/dom/Document.h
@@ -1049,8 +1049,6 @@ public:
     using WeakDocumentSet = WillBeHeapHashSet<RawPtrWillBeWeakMember<Document>>;
     static WeakDocumentSet& liveDocumentSet();
 
-    WebTaskRunner* loadingTaskRunner() const;
-
 protected:
     Document(const DocumentInit&, DocumentClassFlags = DefaultDocumentClass);
 
diff --git a/third_party/WebKit/Source/core/dom/ScriptLoader.cpp b/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
index 8f8b617..e63ea29 100644
--- a/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
+++ b/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
@@ -50,7 +50,6 @@
 #include "core/svg/SVGScriptElement.h"
 #include "platform/MIMETypeRegistry.h"
 #include "platform/weborigin/SecurityOrigin.h"
-#include "public/platform/WebFrameScheduler.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/text/StringBuilder.h"
 #include "wtf/text/StringHash.h"
@@ -260,7 +259,7 @@ bool ScriptLoader::prepareScript(const TextPosition& scriptStartPosition, Legacy
         if (frame) {
             ScriptState* scriptState = ScriptState::forMainWorld(frame);
             if (scriptState->contextIsValid())
-                ScriptStreamer::startStreaming(m_pendingScript, PendingScript::Async, frame->settings(), scriptState, frame->frameScheduler()->loadingTaskRunner());
+                ScriptStreamer::startStreaming(m_pendingScript, PendingScript::Async, frame->settings(), scriptState);
         }
         contextDocument->scriptRunner()->queueScriptForExecution(this, ScriptRunner::ASYNC_EXECUTION);
         // Note that watchForLoad can immediately call notifyFinished.
diff --git a/third_party/WebKit/Source/core/dom/ScriptRunnerTest.cpp b/third_party/WebKit/Source/core/dom/ScriptRunnerTest.cpp
index 68adfdf..f5cf582 100644
--- a/third_party/WebKit/Source/core/dom/ScriptRunnerTest.cpp
+++ b/third_party/WebKit/Source/core/dom/ScriptRunnerTest.cpp
@@ -72,7 +72,7 @@ public:
     explicit MockWebTaskRunner(Deque<OwnPtr<WebTaskRunner::Task>>* tasks) : m_tasks(tasks) { }
     ~MockWebTaskRunner() override { }
 
-    void postTask(const WebTraceLocation&, Task* task) override
+    virtual void postTask(const WebTraceLocation&, Task* task)
     {
         m_tasks->append(adoptPtr(task));
     }
@@ -82,12 +82,6 @@ public:
         ASSERT_NOT_REACHED();
     }
 
-    WebTaskRunner* clone() override
-    {
-        ASSERT_NOT_REACHED();
-        return nullptr;
-    }
-
     Deque<OwnPtr<WebTaskRunner::Task>>* m_tasks; // NOT OWNED
 };
 
diff --git a/third_party/WebKit/Source/core/fetch/FetchContext.h b/third_party/WebKit/Source/core/fetch/FetchContext.h
index 243bf2b..dbcb39b 100644
--- a/third_party/WebKit/Source/core/fetch/FetchContext.h
+++ b/third_party/WebKit/Source/core/fetch/FetchContext.h
@@ -48,7 +48,6 @@ class ResourceLoader;
 class ResourceResponse;
 class ResourceRequest;
 class ResourceTimingInfo;
-class WebTaskRunner;
 
 enum FetchResourceType {
     FetchMainResource,
@@ -107,7 +106,6 @@ public:
 
     virtual bool fetchIncreasePriorities() const { return false; }
     virtual ResourceLoadPriority modifyPriorityForExperiments(ResourceLoadPriority priority, Resource::Type, const FetchRequest&) { return priority; }
-    virtual WebTaskRunner* loadingTaskRunner() const { return nullptr; }
 
 protected:
     FetchContext() { }
diff --git a/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp b/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
index bea44b3..8e09575 100644
--- a/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
+++ b/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
@@ -172,14 +172,6 @@ ResourceFetcher::~ResourceFetcher()
 #endif
 }
 
-WebTaskRunner* ResourceFetcher::loadingTaskRunner()
-{
-    if (!m_context)
-        return nullptr;
-
-    return m_context->loadingTaskRunner();
-}
-
 Resource* ResourceFetcher::cachedResource(const KURL& resourceURL) const
 {
     KURL url = MemoryCache::removeFragmentIdentifierIfNeeded(resourceURL);
diff --git a/third_party/WebKit/Source/core/fetch/ResourceFetcher.h b/third_party/WebKit/Source/core/fetch/ResourceFetcher.h
index 26cdfdc..670f1ca 100644
--- a/third_party/WebKit/Source/core/fetch/ResourceFetcher.h
+++ b/third_party/WebKit/Source/core/fetch/ResourceFetcher.h
@@ -147,8 +147,6 @@ public:
     bool clientDefersImage(const KURL&) const;
     void determineRequestContext(ResourceRequest&, Resource::Type);
 
-    WebTaskRunner* loadingTaskRunner();
-
 private:
     friend class ResourceCacheValidationSuppressor;
 
diff --git a/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp b/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
index 2305adf..be3969e 100644
--- a/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
+++ b/third_party/WebKit/Source/core/fetch/ResourceLoader.cpp
@@ -142,7 +142,6 @@ void ResourceLoader::start()
 
     m_loader = adoptPtr(Platform::current()->createURLLoader());
     ASSERT(m_loader);
-    m_loader->setLoadingTaskRunner(m_fetcher->loadingTaskRunner());
     WrappedResourceRequest wrappedRequest(m_request);
     m_loader->loadAsynchronously(wrappedRequest, this);
 }
diff --git a/third_party/WebKit/Source/core/html/parser/BackgroundHTMLParser.cpp b/third_party/WebKit/Source/core/html/parser/BackgroundHTMLParser.cpp
index e069d7b..3589b67 100644
--- a/third_party/WebKit/Source/core/html/parser/BackgroundHTMLParser.cpp
+++ b/third_party/WebKit/Source/core/html/parser/BackgroundHTMLParser.cpp
@@ -33,7 +33,7 @@
 #include "platform/Task.h"
 #include "platform/ThreadSafeFunctional.h"
 #include "public/platform/Platform.h"
-#include "public/platform/WebTaskRunner.h"
+#include "public/platform/WebScheduler.h"
 #include "wtf/text/TextPosition.h"
 
 namespace blink {
@@ -81,9 +81,9 @@ static void checkThatXSSInfosAreSafeToSendToAnotherThread(const XSSInfoStream& i
 
 #endif
 
-void BackgroundHTMLParser::start(PassRefPtr<WeakReference<BackgroundHTMLParser>> reference, PassOwnPtr<Configuration> config, WebTaskRunner* loadingTaskRunner)
+void BackgroundHTMLParser::start(PassRefPtr<WeakReference<BackgroundHTMLParser>> reference, PassOwnPtr<Configuration> config, WebScheduler* scheduler)
 {
-    new BackgroundHTMLParser(reference, config, loadingTaskRunner);
+    new BackgroundHTMLParser(reference, config, scheduler);
     // Caller must free by calling stop().
 }
 
@@ -93,7 +93,7 @@ BackgroundHTMLParser::Configuration::Configuration()
 {
 }
 
-BackgroundHTMLParser::BackgroundHTMLParser(PassRefPtr<WeakReference<BackgroundHTMLParser>> reference, PassOwnPtr<Configuration> config, WebTaskRunner* loadingTaskRunner)
+BackgroundHTMLParser::BackgroundHTMLParser(PassRefPtr<WeakReference<BackgroundHTMLParser>> reference, PassOwnPtr<Configuration> config, WebScheduler* scheduler)
     : m_weakFactory(reference, this)
     , m_token(adoptPtr(new HTMLToken))
     , m_tokenizer(HTMLTokenizer::create(config->options))
@@ -106,7 +106,7 @@ BackgroundHTMLParser::BackgroundHTMLParser(PassRefPtr<WeakReference<BackgroundHT
     , m_xssAuditor(config->xssAuditor.release())
     , m_preloadScanner(config->preloadScanner.release())
     , m_decoder(config->decoder.release())
-    , m_loadingTaskRunner(loadingTaskRunner)
+    , m_scheduler(scheduler)
     , m_startingScript(false)
 {
     ASSERT(m_outstandingTokenLimit > 0);
@@ -157,7 +157,7 @@ void BackgroundHTMLParser::updateDocument(const String& decodedData)
         m_lastSeenEncodingData = encodingData;
 
         m_xssAuditor->setEncoding(encodingData.encoding());
-        m_loadingTaskRunner->postTask(
+        m_scheduler->loadingTaskRunner()->postTask(
             FROM_HERE,
             threadSafeBind(&HTMLDocumentParser::didReceiveEncodingDataFromBackgroundParser, AllowCrossThreadAccess(m_parser), encodingData));
     }
@@ -291,7 +291,7 @@ void BackgroundHTMLParser::sendTokensToMainThread()
     chunk->startingScript = m_startingScript;
     m_startingScript = false;
 
-    m_loadingTaskRunner->postTask(
+    m_scheduler->loadingTaskRunner()->postTask(
         FROM_HERE,
         new Task(threadSafeBind(&HTMLDocumentParser::didReceiveParsedChunkFromBackgroundParser, AllowCrossThreadAccess(m_parser), chunk.release())));
 
diff --git a/third_party/WebKit/Source/core/html/parser/BackgroundHTMLParser.h b/third_party/WebKit/Source/core/html/parser/BackgroundHTMLParser.h
index 6430f31..6922c31 100644
--- a/third_party/WebKit/Source/core/html/parser/BackgroundHTMLParser.h
+++ b/third_party/WebKit/Source/core/html/parser/BackgroundHTMLParser.h
@@ -42,7 +42,7 @@ namespace blink {
 
 class HTMLDocumentParser;
 class XSSAuditor;
-class WebTaskRunner;
+class WebScheduler;
 
 class BackgroundHTMLParser {
     WTF_MAKE_FAST_ALLOCATED(BackgroundHTMLParser);
@@ -63,7 +63,7 @@ public:
         size_t pendingTokenLimit;
     };
 
-    static void start(PassRefPtr<WeakReference<BackgroundHTMLParser>>, PassOwnPtr<Configuration>, WebTaskRunner*);
+    static void start(PassRefPtr<WeakReference<BackgroundHTMLParser>>, PassOwnPtr<Configuration>, WebScheduler*);
 
     struct Checkpoint {
         WTF_MAKE_FAST_ALLOCATED(CheckPoint);
@@ -90,7 +90,7 @@ public:
     void forcePlaintextForTextDocument();
 
 private:
-    BackgroundHTMLParser(PassRefPtr<WeakReference<BackgroundHTMLParser>>, PassOwnPtr<Configuration>, WebTaskRunner*);
+    BackgroundHTMLParser(PassRefPtr<WeakReference<BackgroundHTMLParser>>, PassOwnPtr<Configuration>, WebScheduler*);
     ~BackgroundHTMLParser();
 
     void appendDecodedBytes(const String&);
@@ -118,7 +118,7 @@ private:
     OwnPtr<TokenPreloadScanner> m_preloadScanner;
     OwnPtr<TextResourceDecoder> m_decoder;
     DocumentEncodingData m_lastSeenEncodingData;
-    WebTaskRunner* m_loadingTaskRunner; // NOT OWNED, task runner will outlive BackgroundHTMLParserr
+    WebScheduler* m_scheduler; // NOT OWNED, scheduler will outlive BackgroundHTMLParser
 
     bool m_startingScript;
 };
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp b/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp
index 6a9670d..868e71e 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp
+++ b/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp
@@ -50,7 +50,6 @@
 #include "platform/TraceEvent.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/Platform.h"
-#include "public/platform/WebFrameScheduler.h"
 #include "public/platform/WebScheduler.h"
 #include "public/platform/WebThread.h"
 #include "wtf/RefCounted.h"
@@ -144,8 +143,7 @@ HTMLDocumentParser::HTMLDocumentParser(HTMLDocument& document, bool reportErrors
     , m_tokenizer(syncPolicy == ForceSynchronousParsing ? HTMLTokenizer::create(m_options) : nullptr)
     , m_scriptRunner(HTMLScriptRunner::create(&document, this))
     , m_treeBuilder(HTMLTreeBuilder::create(this, &document, parserContentPolicy(), reportErrors, m_options))
-    , m_loadingTaskRunner(adoptPtr(document.loadingTaskRunner()->clone()))
-    , m_parserScheduler(HTMLParserScheduler::create(this, m_loadingTaskRunner.get()))
+    , m_parserScheduler(HTMLParserScheduler::create(this))
     , m_xssAuditorDelegate(&document)
     , m_weakFactory(this)
     , m_preloader(HTMLResourcePreloader::create(document))
@@ -168,7 +166,6 @@ HTMLDocumentParser::HTMLDocumentParser(DocumentFragment* fragment, Element* cont
     , m_token(adoptPtr(new HTMLToken))
     , m_tokenizer(HTMLTokenizer::create(m_options))
     , m_treeBuilder(HTMLTreeBuilder::create(this, fragment, contextElement, this->parserContentPolicy(), m_options))
-    , m_loadingTaskRunner(adoptPtr(fragment->document().loadingTaskRunner()->clone()))
     , m_xssAuditorDelegate(&fragment->document())
     , m_weakFactory(this)
     , m_shouldUseThreading(false)
@@ -804,7 +801,7 @@ void HTMLDocumentParser::startBackgroundParser()
     ASSERT(config->xssAuditor->isSafeToSendToAnotherThread());
     ASSERT(config->preloadScanner->isSafeToSendToAnotherThread());
     HTMLParserThread::shared()->postTask(threadSafeBind(&BackgroundHTMLParser::start, reference.release(), config.release(),
-        AllowCrossThreadAccess(m_loadingTaskRunner.get())));
+        AllowCrossThreadAccess(Platform::current()->currentThread()->scheduler())));
 }
 
 void HTMLDocumentParser::stopBackgroundParser()
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h b/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h
index f41d9b03..8fba554 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h
+++ b/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h
@@ -187,7 +187,6 @@ private:
     OwnPtrWillBeMember<HTMLTreeBuilder> m_treeBuilder;
     OwnPtr<HTMLPreloadScanner> m_preloadScanner;
     OwnPtr<HTMLPreloadScanner> m_insertionPreloadScanner;
-    OwnPtr<WebTaskRunner> m_loadingTaskRunner;
     OwnPtr<HTMLParserScheduler> m_parserScheduler;
     HTMLSourceTracker m_sourceTracker;
     TextPosition m_textPosition;
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLParserScheduler.cpp b/third_party/WebKit/Source/core/html/parser/HTMLParserScheduler.cpp
index 58a3ded..c15e43b5 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLParserScheduler.cpp
+++ b/third_party/WebKit/Source/core/html/parser/HTMLParserScheduler.cpp
@@ -82,9 +82,9 @@ void SpeculationsPumpSession::addedElementTokens(size_t count)
     m_processedElementTokens += count;
 }
 
-HTMLParserScheduler::HTMLParserScheduler(HTMLDocumentParser* parser, WebTaskRunner* loadingTaskRunner)
+HTMLParserScheduler::HTMLParserScheduler(HTMLDocumentParser* parser)
     : m_parser(parser)
-    , m_loadingTaskRunner(adoptPtr(loadingTaskRunner->clone()))
+    , m_loadingTaskRunner(Platform::current()->currentThread()->scheduler()->loadingTaskRunner())
     , m_cancellableContinueParse(CancellableTaskFactory::create(this, &HTMLParserScheduler::continueParsing))
     , m_isSuspendedWithActiveTimer(false)
 {
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLParserScheduler.h b/third_party/WebKit/Source/core/html/parser/HTMLParserScheduler.h
index ad3ccaa..d7878db 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLParserScheduler.h
+++ b/third_party/WebKit/Source/core/html/parser/HTMLParserScheduler.h
@@ -36,7 +36,6 @@ namespace blink {
 
 class Document;
 class HTMLDocumentParser;
-class WebTaskRunner;
 
 class ActiveParserSession : public NestingLevelIncrementer {
     STACK_ALLOCATED();
@@ -73,9 +72,9 @@ private:
 class HTMLParserScheduler {
     WTF_MAKE_NONCOPYABLE(HTMLParserScheduler); WTF_MAKE_FAST_ALLOCATED(HTMLParserScheduler);
 public:
-    static PassOwnPtr<HTMLParserScheduler> create(HTMLDocumentParser* parser, WebTaskRunner* loadingTaskRunner)
+    static PassOwnPtr<HTMLParserScheduler> create(HTMLDocumentParser* parser)
     {
-        return adoptPtr(new HTMLParserScheduler(parser, loadingTaskRunner));
+        return adoptPtr(new HTMLParserScheduler(parser));
     }
     ~HTMLParserScheduler();
 
@@ -99,13 +98,13 @@ public:
     void detach(); // Clear active tasks if any.
 
 private:
-    HTMLParserScheduler(HTMLDocumentParser*, WebTaskRunner*);
+    explicit HTMLParserScheduler(HTMLDocumentParser*);
 
     bool shouldYield(const SpeculationsPumpSession&, bool startingScript) const;
     void continueParsing();
 
     HTMLDocumentParser* m_parser;
-    OwnPtr<WebTaskRunner> m_loadingTaskRunner;
+    WebTaskRunner* m_loadingTaskRunner; // NOT OWNED
 
     OwnPtr<CancellableTaskFactory> m_cancellableContinueParse;
     bool m_isSuspendedWithActiveTimer;
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLScriptRunner.cpp b/third_party/WebKit/Source/core/html/parser/HTMLScriptRunner.cpp
index 35b1258..3d80848 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLScriptRunner.cpp
+++ b/third_party/WebKit/Source/core/html/parser/HTMLScriptRunner.cpp
@@ -40,7 +40,6 @@
 #include "core/html/parser/NestingLevelIncrementer.h"
 #include "platform/NotImplemented.h"
 #include "public/platform/Platform.h"
-#include "public/platform/WebFrameScheduler.h"
 
 namespace blink {
 
@@ -288,7 +287,7 @@ void HTMLScriptRunner::requestParsingBlockingScript(Element* element)
         if (m_document->frame()) {
             ScriptState* scriptState = ScriptState::forMainWorld(m_document->frame());
             if (scriptState->contextIsValid())
-                ScriptStreamer::startStreaming(m_parserBlockingScript, PendingScript::ParsingBlocking, m_document->frame()->settings(), scriptState, m_document->loadingTaskRunner());
+                ScriptStreamer::startStreaming(m_parserBlockingScript, PendingScript::ParsingBlocking, m_document->frame()->settings(), scriptState);
         }
 
         m_parserBlockingScript.watchForLoad(this);
@@ -304,7 +303,7 @@ void HTMLScriptRunner::requestDeferredScript(Element* element)
     if (m_document->frame() && !pendingScript.isReady()) {
         ScriptState* scriptState = ScriptState::forMainWorld(m_document->frame());
         if (scriptState->contextIsValid())
-            ScriptStreamer::startStreaming(pendingScript, PendingScript::Deferred, m_document->frame()->settings(), scriptState, m_document->loadingTaskRunner());
+            ScriptStreamer::startStreaming(pendingScript, PendingScript::Deferred, m_document->frame()->settings(), scriptState);
     }
 
     ASSERT(pendingScript.resource());
diff --git a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
index 5fb9d1e..527a8d1 100644
--- a/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameFetchContext.cpp
@@ -64,7 +64,6 @@
 #include "platform/network/ResourceTimingInfo.h"
 #include "platform/weborigin/SchemeRegistry.h"
 #include "platform/weborigin/SecurityPolicy.h"
-#include "public/platform/WebFrameScheduler.h"
 
 #include <algorithm>
 
@@ -733,11 +732,6 @@ ResourceLoadPriority FrameFetchContext::modifyPriorityForExperiments(ResourceLoa
     return static_cast<ResourceLoadPriority>(modifiedPriority);
 }
 
-WebTaskRunner* FrameFetchContext::loadingTaskRunner() const
-{
-    return frame()->frameScheduler()->loadingTaskRunner();
-}
-
 DEFINE_TRACE(FrameFetchContext)
 {
     visitor->trace(m_document);
diff --git a/third_party/WebKit/Source/core/loader/FrameFetchContext.h b/third_party/WebKit/Source/core/loader/FrameFetchContext.h
index a71afae..de5c516 100644
--- a/third_party/WebKit/Source/core/loader/FrameFetchContext.h
+++ b/third_party/WebKit/Source/core/loader/FrameFetchContext.h
@@ -109,8 +109,6 @@ public:
     void countClientHintsResourceWidth() override;
     void countClientHintsViewportWidth() override;
 
-    WebTaskRunner* loadingTaskRunner() const override;
-
     DECLARE_VIRTUAL_TRACE();
 
 private:
diff --git a/third_party/WebKit/Source/core/loader/FrameLoader.cpp b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
index e25c9cb..05fe067 100644
--- a/third_party/WebKit/Source/core/loader/FrameLoader.cpp
+++ b/third_party/WebKit/Source/core/loader/FrameLoader.cpp
@@ -1072,8 +1072,7 @@ bool FrameLoader::prepareForCommit()
     if (m_frame->document())
         m_frame->document()->detach();
     m_documentLoader = m_provisionalDocumentLoader.release();
-    m_frame->updateFrameSecurityOrigin();
-    
+
     return true;
 }
 
diff --git a/third_party/WebKit/Source/platform/TimerTest.cpp b/third_party/WebKit/Source/platform/TimerTest.cpp
index 6db91cb..9a0900c 100644
--- a/third_party/WebKit/Source/platform/TimerTest.cpp
+++ b/third_party/WebKit/Source/platform/TimerTest.cpp
@@ -77,7 +77,7 @@ public:
     explicit MockWebTaskRunner(std::priority_queue<DelayedTask>* timerTasks) : m_timerTasks(timerTasks) { }
     ~MockWebTaskRunner() override { }
 
-    void postTask(const WebTraceLocation&, Task* task) override
+    virtual void postTask(const WebTraceLocation&, Task* task)
     {
         m_timerTasks->push(DelayedTask(task, 0));
     }
@@ -87,12 +87,6 @@ public:
         m_timerTasks->push(DelayedTask(task, delayMs * 0.001));
     }
 
-    WebTaskRunner* clone() override
-    {
-        ASSERT_NOT_REACHED();
-        return nullptr;
-    }
-
     std::priority_queue<DelayedTask>* m_timerTasks; // NOT OWNED
 };
 
diff --git a/third_party/WebKit/Source/platform/graphics/RecordingImageBufferSurfaceTest.cpp b/third_party/WebKit/Source/platform/graphics/RecordingImageBufferSurfaceTest.cpp
index abc94b7..8cf1c04 100644
--- a/third_party/WebKit/Source/platform/graphics/RecordingImageBufferSurfaceTest.cpp
+++ b/third_party/WebKit/Source/platform/graphics/RecordingImageBufferSurfaceTest.cpp
@@ -260,7 +260,7 @@ private:
         MockWebTaskRunner() : m_task(0) { }
         ~MockWebTaskRunner() override { }
 
-        void postTask(const WebTraceLocation&, Task* task) override
+        virtual void postTask(const WebTraceLocation&, Task* task)
         {
             EXPECT_EQ((Task*)0, m_task);
             m_task = task;
@@ -268,12 +268,6 @@ private:
 
         void postDelayedTask(const WebTraceLocation&, Task*, double delayMs) override { ASSERT_NOT_REACHED(); };
 
-        WebTaskRunner* clone() override
-        {
-            ASSERT_NOT_REACHED();
-            return nullptr;
-        }
-
         Task* m_task;
     };
 
diff --git a/third_party/WebKit/Source/web/AssociatedURLLoader.cpp b/third_party/WebKit/Source/web/AssociatedURLLoader.cpp
index a167fc4..bd33455 100644
--- a/third_party/WebKit/Source/web/AssociatedURLLoader.cpp
+++ b/third_party/WebKit/Source/web/AssociatedURLLoader.cpp
@@ -383,9 +383,4 @@ void AssociatedURLLoader::setDefersLoading(bool defersLoading)
         m_loader->setDefersLoading(defersLoading);
 }
 
-void AssociatedURLLoader::setLoadingTaskRunner(blink::WebTaskRunner*)
-{
-    // TODO(alexclarke): Maybe support this one day if it proves worthwhile.
-}
-
 } // namespace blink
diff --git a/third_party/WebKit/Source/web/AssociatedURLLoader.h b/third_party/WebKit/Source/web/AssociatedURLLoader.h
index 6dcd06e..41b0c26 100644
--- a/third_party/WebKit/Source/web/AssociatedURLLoader.h
+++ b/third_party/WebKit/Source/web/AssociatedURLLoader.h
@@ -54,7 +54,6 @@ public:
     void loadAsynchronously(const WebURLRequest&, WebURLLoaderClient*) override;
     void cancel() override;
     void setDefersLoading(bool) override;
-    void setLoadingTaskRunner(blink::WebTaskRunner*) override;
 
 private: