[subresource_filter] SB throttle can send multiple speculative requests.

content/public/test/cancelling_navigation_throttle.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_PUBLIC_TEST_CANCELLING_NAVIGATION_THROTTLE_H_
+#define CONTENT_PUBLIC_TEST_CANCELLING_NAVIGATION_THROTTLE_H_
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "content/public/browser/navigation_throttle.h"
+
+namespace content {
+
+class NavigationHandle;
+
+// This class can be used to cancel navigations synchronously or asynchronously
+// at a specific time in the NavigationThrottle lifecycle.
+//
+// Consider using it in conjunction with NavigationSimulator.

[clamy, 2017/04/24 12:07:12]

nit: Could you add a
TODO(clamy): Check if this could be used in unit tests exercising
NavigationThrottle code.
?

[Charlie Harrison, 2017/04/24 18:25:10]

Done.

+class CancellingNavigationThrottle : public NavigationThrottle {
+ public:
+  enum CancelTime {

[clamy, 2017/04/24 12:07:12]

nit: could this be made an enum class?

[Charlie Harrison, 2017/04/24 18:25:10]

It could, but tests using these enums are already extremely verbose without the
extra "CancelTime" . I'd prefer to keep as-is unless you feel strongly.

+    WILL_START_REQUEST,
+    WILL_REDIRECT_REQUEST,
+    WILL_PROCESS_RESPONSE,
+    NEVER,
+  };
+
+  enum ResultSynchrony {
+    SYNCHRONOUS,
+    ASYNCHRONOUS,
+  };
+
+  CancellingNavigationThrottle(NavigationHandle* handle,
+                               CancelTime cancel_time,
+                               ResultSynchrony sync);
+  ~CancellingNavigationThrottle() override;
+
+  NavigationThrottle::ThrottleCheckResult WillStartRequest() override;
+  NavigationThrottle::ThrottleCheckResult WillRedirectRequest() override;
+  NavigationThrottle::ThrottleCheckResult WillProcessResponse() override;
+
+ private:
+  NavigationThrottle::ThrottleCheckResult ProcessState(bool should_cancel);
+  void MaybeCancel(bool cancel);
+
+ private:
+  const CancelTime cancel_time_;
+  const ResultSynchrony sync_;
+
+  base::WeakPtrFactory<CancellingNavigationThrottle> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CancellingNavigationThrottle);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_TEST_CANCELLING_NAVIGATION_THROTTLE_H_