Use ParentFrameTaskRunners in WorkerLoaderProxyProvider::postTaskToLoader impls

Implementations of WorkerLoaderProxyProvider::postTaskToLoader have used
ExecutionContext::postTask to post tasks to the main thread. However,
the posted tasks are unexpectedly throttled, and that delays the startup
time of service workers.
This CL replaces ExecutionContext::postTask there with ParentFrameTaskRunners
and WebTaskRunner::postTask, so that the posted task is routed to suitable
task runners.

BUG=667310, 671084

Review-Url: https://codereview.chromium.org/2574703002
Cr-Commit-Position: refs/heads/master@{#438146}

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

@@ -48,6 +48,11 @@ class CORE_EXPORT ExecutionContextTask {
   ExecutionContextTask() {}
   virtual ~ExecutionContextTask() {}
   virtual void performTask(ExecutionContext*) = 0;
+
+  void performTaskIfContextIsValid(ExecutionContext* context) {
+    if (context)
+      performTask(context);
+  }
 };
 
 namespace internal {

third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp

@@ -240,6 +240,8 @@ class WorkerThreadableLoaderTestHelper : public ThreadableLoaderTestHelper,
   void onSetUp() override {
     m_mockWorkerReportingProxy = WTF::makeUnique<MockWorkerReportingProxy>();
     m_securityOrigin = document().getSecurityOrigin();
+    m_parentFrameTaskRunners =
+        ParentFrameTaskRunners::create(&m_dummyPageHolder->frame());
     m_workerThread = WTF::wrapUnique(new WorkerThreadForTest(
         this, *m_mockWorkerReportingProxy, m_threadHeapMode));
 
@@ -329,7 +331,12 @@ class WorkerThreadableLoaderTestHelper : public ThreadableLoaderTestHelper,
                         std::unique_ptr<ExecutionContextTask> task) override {
     DCHECK(m_workerThread);
     DCHECK(m_workerThread->isCurrentThread());
-    document().postTask(location, std::move(task));
+    m_parentFrameTaskRunners->get(TaskType::Networking)
+        ->postTask(
+            BLINK_FROM_HERE,
+            crossThreadBind(&ExecutionContextTask::performTaskIfContextIsValid,
+                            WTF::passed(std::move(task)),
+                            wrapCrossThreadWeakPersistent(&document())));
   }
 
   void postTaskToWorkerGlobalScope(
@@ -344,6 +351,7 @@ class WorkerThreadableLoaderTestHelper : public ThreadableLoaderTestHelper,
   std::unique_ptr<WorkerThreadForTest> m_workerThread;
 
   std::unique_ptr<DummyPageHolder> m_dummyPageHolder;
+  Persistent<ParentFrameTaskRunners> m_parentFrameTaskRunners;
   Checkpoint m_checkpoint;
   // |m_loader| must be touched only from the worker thread only.
   CrossThreadPersistent<ThreadableLoader> m_loader;

third_party/WebKit/Source/core/workers/ThreadedMessagingProxyBase.cpp

@@ -74,9 +74,12 @@ void ThreadedMessagingProxyBase::postTaskToLoader(
     const WebTraceLocation& location,
     std::unique_ptr<ExecutionContextTask> task) {
   DCHECK(getExecutionContext()->isDocument());
-  // TODO(hiroshige,yuryu): Make this not use ExecutionContextTask and use
-  // m_parentFrameTaskRunners->get(TaskType::Networking) instead.
-  getExecutionContext()->postTask(location, std::move(task));
+  m_parentFrameTaskRunners->get(TaskType::Networking)
+      ->postTask(BLINK_FROM_HERE,
+                 crossThreadBind(
+                     &ExecutionContextTask::performTaskIfContextIsValid,
+                     WTF::passed(std::move(task)),
+                     wrapCrossThreadWeakPersistent(getExecutionContext())));
 }
 
 void ThreadedMessagingProxyBase::countFeature(UseCounter::Feature feature) {

third_party/WebKit/Source/web/WebEmbeddedWorkerImpl.cpp

@@ -263,10 +263,13 @@ void WebEmbeddedWorkerImpl::postMessageToPageInspector(const String& message) {
 void WebEmbeddedWorkerImpl::postTaskToLoader(
     const WebTraceLocation& location,
     std::unique_ptr<ExecutionContextTask> task) {
-  // TODO(hiroshige,yuryu): Make this not use ExecutionContextTask and
-  // consider using m_mainThreadTaskRunners->get(TaskType::Networking)
-  // instead.
-  m_mainFrame->frame()->document()->postTask(location, std::move(task));
+  m_mainThreadTaskRunners->get(TaskType::Networking)
+      ->postTask(
+          BLINK_FROM_HERE,
+          crossThreadBind(
+              &ExecutionContextTask::performTaskIfContextIsValid,
+              WTF::passed(std::move(task)),
+              wrapCrossThreadWeakPersistent(m_mainFrame->frame()->document())));
 }
 
 void WebEmbeddedWorkerImpl::postTaskToWorkerGlobalScope(

third_party/WebKit/Source/web/WebSharedWorkerImpl.cpp

@@ -51,6 +51,7 @@
 #include "platform/CrossThreadFunctional.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/heap/Handle.h"
+#include "platform/heap/Persistent.h"
 #include "platform/network/ContentSecurityPolicyParsers.h"
 #include "platform/network/ResourceResponse.h"
 #include "platform/weborigin/KURL.h"
@@ -306,10 +307,12 @@ void WebSharedWorkerImpl::didTerminateWorkerThreadOnMainThread() {
 void WebSharedWorkerImpl::postTaskToLoader(
     const WebTraceLocation& location,
     std::unique_ptr<ExecutionContextTask> task) {
-  // TODO(hiroshige,yuryu): Make this not use ExecutionContextTask and
-  // consider using m_parentFrameTaskRunners->get(TaskType::Networking)
-  // instead.
-  m_mainFrame->frame()->document()->postTask(location, std::move(task));
+  m_parentFrameTaskRunners->get(TaskType::Networking)
+      ->postTask(FROM_HERE,
+                 crossThreadBind(
+                     &ExecutionContextTask::performTaskIfContextIsValid,
+                     WTF::passed(std::move(task)),
+                     wrapCrossThreadWeakPersistent(m_loadingDocument.get())));
 }
 
 void WebSharedWorkerImpl::postTaskToWorkerGlobalScope(