Worker: Provide a way to access parent frame task runners from a worker thread

third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.cpp

Index: third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.cpp
diff --git a/third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.cpp b/third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.cpp
index b3d1850adf7115988cb12ace8c85a4223eb20caa..920f1b79cda39d3dc4961a0748c19933db1f1952 100644
--- a/third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.cpp
+++ b/third_party/WebKit/Source/web/ServiceWorkerGlobalScopeProxy.cpp
@@ -38,6 +38,7 @@
 #include "core/dom/MessagePort.h"
 #include "core/inspector/ConsoleMessage.h"
 #include "core/origin_trials/OriginTrials.h"
+#include "core/workers/ParentFrameTaskRunners.h"
 #include "core/workers/WorkerGlobalScope.h"
 #include "core/workers/WorkerThread.h"
 #include "modules/background_sync/SyncEvent.h"
@@ -86,6 +87,7 @@ ServiceWorkerGlobalScopeProxy::~ServiceWorkerGlobalScopeProxy() {
 
 DEFINE_TRACE(ServiceWorkerGlobalScopeProxy) {
   visitor->trace(m_document);
+  visitor->trace(m_parentFrameTaskRunners);
   visitor->trace(m_pendingPreloadFetchEvents);
 }
 
@@ -357,6 +359,11 @@ void ServiceWorkerGlobalScopeProxy::postMessageToPageInspector(
                             crossThreadUnretained(m_embeddedWorker), message));
 }
 
+ParentFrameTaskRunners*
+ServiceWorkerGlobalScopeProxy::getParentFrameTaskRunners() {
+  return m_parentFrameTaskRunners.get();
+}
+
 void ServiceWorkerGlobalScopeProxy::didCreateWorkerGlobalScope(
     WorkerOrWorkletGlobalScope* workerGlobalScope) {
   DCHECK(!m_workerGlobalScope);
@@ -416,7 +423,13 @@ ServiceWorkerGlobalScopeProxy::ServiceWorkerGlobalScopeProxy(
     : m_embeddedWorker(&embeddedWorker),
       m_document(&document),
       m_client(&client),
-      m_workerGlobalScope(nullptr) {}
+      m_workerGlobalScope(nullptr) {
+  // We have a dummy document here for loading but it doesn't really represent
+  // the document/frame of associated document(s) for this worker. Here we
+  // populate the task runners with null document not to confuse the frame
+  // scheduler (which will end up using the thread's default task runner).
+  m_parentFrameTaskRunners = ParentFrameTaskRunners::create(nullptr);

[haraken, 2016/11/22 01:26:17]

When is the correct document set to m_parentFrameTaskRunners?

[nhiroki, 2016/11/22 03:27:20]

In my understanding, there is no correct document for a service worker because
it may associate with multiple documents or no document, for example, when a
service worker is initiated by push messaging.

Choosing an arbitrary document when a service worker gets associated with some
documents could be an option, but it could be harmful to switch per-frame task
runners in the middle of life of the worker.

Another option would be to adopt a dummy document, I'm not sure if this is more
reasonable than using a default task runners though. WDYT?

+}
 
 void ServiceWorkerGlobalScopeProxy::detach() {
   m_embeddedWorker = nullptr;