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

third_party/WebKit/Source/core/loader/ThreadableLoadingContext.h

Index: third_party/WebKit/Source/core/loader/ThreadableLoadingContext.h
diff --git a/third_party/WebKit/Source/core/loader/ThreadableLoadingContext.h b/third_party/WebKit/Source/core/loader/ThreadableLoadingContext.h
new file mode 100644
index 0000000000000000000000000000000000000000..eee4ddbd070de7232357f6d57c9d31e5286ecf4f
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+++ b/third_party/WebKit/Source/core/loader/ThreadableLoadingContext.h
@@ -0,0 +1,54 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ThreadableLoadingContext_h
+#define ThreadableLoadingContext_h
+
+#include "core/CoreExport.h"
+#include "core/dom/TaskRunnerHelper.h"
+#include "core/frame/UseCounter.h"
+#include "platform/heap/GarbageCollected.h"
+#include "platform/weborigin/KURL.h"
+#include "wtf/Forward.h"
+#include "wtf/Noncopyable.h"
+
+namespace blink {
+
+class Document;
+class ResourceFetcher;
+class SecurityOrigin;
+class WebTaskRunner;
+
+// An abstract interface for top-level loading context.
+// This should be accessed only from the thread where the loading
+// context is bound to (e.g. on the main thread).
+class CORE_EXPORT ThreadableLoadingContext
+    : public GarbageCollected<ThreadableLoadingContext> {
+  WTF_MAKE_NONCOPYABLE(ThreadableLoadingContext);
+
+ public:
+  static ThreadableLoadingContext* create(Document&);
+
+  ThreadableLoadingContext() = default;
+  virtual ~ThreadableLoadingContext() = default;
+
+  virtual bool isContextThread() const = 0;
+
+  virtual ResourceFetcher* getResourceFetcher() = 0;
+  virtual SecurityOrigin* getSecurityOrigin() = 0;
+  virtual bool isSecureContext() const = 0;
+  virtual KURL firstPartyForCookies() const = 0;
+  virtual String userAgent() const = 0;
+  virtual RefPtr<WebTaskRunner> getTaskRunner(TaskType) = 0;
+  virtual void recordUseCount(UseCounter::Feature) = 0;
+
+  // TODO(kinuko): Try getting rid of dependency to Document.
+  virtual Document* getLoadingDocument() { return nullptr; }
+
+  DEFINE_INLINE_VIRTUAL_TRACE() {}
+};
+
+}  // namespace blink
+
+#endif  // ThreadableLoadingContext_h