Refactor ResourceHandler API.

content/browser/loader/null_resource_controller.h

+// 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 CONTENT_BROWSER_LOADER_NULL_RESOURCE_CONTROLLER_H_
+#define CONTENT_BROWSER_LOADER_NULL_RESOURCE_CONTROLLER_H_
+
+#include "base/macros.h"
+#include "content/browser/loader/resource_controller.h"
+
+namespace content {
+
+// A pseudo-ResourceController that just tracks whether it was resumed or not.
+// Only intended when calling into ResourceHandlers that either much resume the
+// request, or when the consumer doesn't care if the request was resumed or not.
+// TODO(mmenke): Modify consumers so they don't need to use this class.
+class NullResourceController : public ResourceController {
+ public:
+  explicit NullResourceController(bool* was_resumed);
+  ~NullResourceController() override;
+
+  // ResourceController implementation:
+  void Cancel() override;
+  void CancelAndIgnore() override;
+  void CancelWithError(int error_code) override;
+  void Resume() override;
+
+ private:
+  bool* was_resumed_;
+
+  DISALLOW_COPY_AND_ASSIGN(NullResourceController);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_LOADER_NULL_RESOURCE_CONTROLLER_H_