service worker: Add NavigationPreload runtime flag and skeleton interface

third_party/WebKit/Source/modules/serviceworkers/NavigationPreloadManager.h

+// Copyright 2016 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 NavigationPreloadManager_h
+#define NavigationPreloadManager_h
+
+#include "bindings/core/v8/ScriptPromise.h"
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class NavigationPreloadManager final
+    : public GarbageCollected<NavigationPreloadManager>,
+      public ScriptWrappable {
+  DEFINE_WRAPPERTYPEINFO();
+
+ public:
+  static NavigationPreloadManager* create() {
+    return new NavigationPreloadManager();
+  }
+
+  ScriptPromise enable(ScriptState*);
+  ScriptPromise disable(ScriptState*);
+  ScriptPromise setHeaderValue(ScriptState*, const String& value);
+  ScriptPromise getState(ScriptState*);
+
+  DEFINE_INLINE_TRACE() {}
+
+ private:
+  NavigationPreloadManager();
+};
+
+}  // namespace blink
+
+#endif  // NavigationPreloadManager_h