Introduce ThreadableLoadingContext: make threaded loading code one step away from Document

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

Index: third_party/WebKit/Source/core/workers/ThreadedMessagingProxyBase.cpp
diff --git a/third_party/WebKit/Source/core/workers/ThreadedMessagingProxyBase.cpp b/third_party/WebKit/Source/core/workers/ThreadedMessagingProxyBase.cpp
index a3fe6be4d0935e54744a8528e721856ee7dc9953..c547f0a4161244d08ecdd548b80ad3a2370f7e6a 100644
--- a/third_party/WebKit/Source/core/workers/ThreadedMessagingProxyBase.cpp
+++ b/third_party/WebKit/Source/core/workers/ThreadedMessagingProxyBase.cpp
@@ -6,9 +6,9 @@
 
 #include "bindings/core/v8/SourceLocation.h"
 #include "core/dom/Document.h"
-#include "core/dom/ExecutionContextTask.h"
 #include "core/frame/Deprecation.h"
 #include "core/loader/DocumentLoader.h"
+#include "core/loader/LoadingContext.h"
 #include "core/workers/WorkerInspectorProxy.h"
 #include "core/workers/WorkerThreadStartupData.h"
 #include "wtf/CurrentTime.h"
@@ -77,9 +77,11 @@ void ThreadedMessagingProxyBase::postTaskToLoader(
       ->postTask(BLINK_FROM_HERE, std::move(task));
 }
 
-ExecutionContext* ThreadedMessagingProxyBase::getLoaderExecutionContext() {
+LoadingContext* ThreadedMessagingProxyBase::getLoadingContext() {
   DCHECK(isParentContextThread());
-  return getExecutionContext();
+  if (!m_loadingContext)
+    m_loadingContext = LoadingContext::create(*toDocument(m_executionContext));
+  return m_loadingContext;
 }
 
 void ThreadedMessagingProxyBase::countFeature(UseCounter::Feature feature) {