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

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

Index: third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp
diff --git a/third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp b/third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp
index 240f0b237e3e0982fdce58a43f023fbaf6ada875..7d35cb15d91f14b03230612d1b0f8e8f15041f3a 100644
--- a/third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp
+++ b/third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp
@@ -4,7 +4,9 @@
 
 #include "core/loader/ThreadableLoader.h"
 
+#include <memory>
 #include "core/loader/DocumentThreadableLoader.h"
+#include "core/loader/LoadingContext.h"
 #include "core/loader/ThreadableLoaderClient.h"
 #include "core/loader/WorkerThreadableLoader.h"
 #include "core/testing/DummyPageHolder.h"
@@ -32,7 +34,6 @@
 #include "wtf/Functional.h"
 #include "wtf/PtrUtil.h"
 #include "wtf/RefPtr.h"
-#include <memory>
 
 namespace blink {
 
@@ -241,6 +242,7 @@ class WorkerThreadableLoaderTestHelper : public ThreadableLoaderTestHelper,
         ParentFrameTaskRunners::create(&m_dummyPageHolder->frame());
     m_workerThread = WTF::wrapUnique(
         new WorkerThreadForTest(this, *m_mockWorkerReportingProxy));
+    m_loadingContext = LoadingContext::create(document());
 
     expectWorkerLifetimeReportingCalls();
     m_workerThread->startWithSourceCode(m_securityOrigin.get(),
@@ -341,7 +343,9 @@ class WorkerThreadableLoaderTestHelper : public ThreadableLoaderTestHelper,
     m_workerThread->postTask(location, std::move(task));
   }
 
-  ExecutionContext* getLoaderExecutionContext() override { return &document(); }
+  LoadingContext* getLoadingContext() override {
+    return m_loadingContext.get();
+  }
 
   RefPtr<SecurityOrigin> m_securityOrigin;
   std::unique_ptr<MockWorkerReportingProxy> m_mockWorkerReportingProxy;
@@ -353,6 +357,8 @@ class WorkerThreadableLoaderTestHelper : public ThreadableLoaderTestHelper,
   Checkpoint m_checkpoint;
   // |m_loader| must be touched only from the worker thread only.
   CrossThreadPersistent<ThreadableLoader> m_loader;
+
+  Persistent<LoadingContext> m_loadingContext;
 };
 
 class ThreadableLoaderTest