[subresource_filter] SB throttle can send multiple speculative requests.

components/subresource_filter/content/browser/subresource_filter_safe_browsing_client.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 COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_SUBRESOURCE_FILTER_SAFE_BROWSING_CLIENT_H_
+#define COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_SUBRESOURCE_FILTER_SAFE_BROWSING_CLIENT_H_
+
+#include <stddef.h>
+
+#include <map>
+#include <memory>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
+#include "components/safe_browsing_db/util.h"
+#include "components/safe_browsing_db/v4_local_database_manager.h"
+
+class GURL;
+
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace subresource_filter {
+
+class SubresourceFilterSafeBrowsingActivationThrottle;
+class SubresourceFilterSafeBrowsingClientRequest;
+
+// Created on the UI thread but used on the IO thread to communicate with the
+// safe browsing service.
+//
+// The class is expected to accompany a single navigation, and can maintain many
+// database requests. It will cancel cancel any outgoing requests when it is
+// destroyed.
+class SubresourceFilterSafeBrowsingClient {
+ public:
+  struct CheckResult {
+    size_t request_id = 0;
+    safe_browsing::SBThreatType threat_type =
+        safe_browsing::SBThreatType::SB_THREAT_TYPE_SAFE;
+    safe_browsing::ThreatPatternType pattern_type =
+        safe_browsing::ThreatPatternType::NONE;
+    base::TimeDelta check_time;
+    bool finished = false;
+  };
+
+  SubresourceFilterSafeBrowsingClient(
+      scoped_refptr<safe_browsing::SafeBrowsingDatabaseManager>
+          database_manager,
+      base::WeakPtr<SubresourceFilterSafeBrowsingActivationThrottle> throttle,
+      scoped_refptr<base::SingleThreadTaskRunner> io_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner);

[Nathan Parker, 2017/05/03 00:00:42]

The args here are different than in the .cc file.  Is there a more accurate name
for these task runners, and could you do with just using the global io/ui task
runners?

[Charlie Harrison, 2017/05/03 01:20:30]

Renamed the task runner to throttle_task_runner. AFAIK grabbing the current task
runner (as we do in the throttle) is the preferred way of doing things now to
make code more sequence friendly.

Not sure of a better name for io_task_runner, but we inject it in tests to use
the mock time task runner (for artificially advancing time).

+
+  ~SubresourceFilterSafeBrowsingClient();
+
+  void CheckUrlOnIO(const GURL& url, size_t request_id);
+
+  void OnCheckBrowseUrlResult(
+      SubresourceFilterSafeBrowsingClientRequest* request,
+      const CheckResult& check_result);
+
+ private:
+  // This is stored as a map to allow for ergonomic deletion.
+  std::map<SubresourceFilterSafeBrowsingClientRequest*,

[Nathan Parker, 2017/05/03 00:00:42]

nit: flat_map would likely have better RAM/CPU performance. Your choice.

[Charlie Harrison, 2017/05/03 01:20:30]

Good call, done.

+           std::unique_ptr<SubresourceFilterSafeBrowsingClientRequest>>
+      requests_;
+
+  scoped_refptr<safe_browsing::SafeBrowsingDatabaseManager> database_manager_;
+
+  base::WeakPtr<SubresourceFilterSafeBrowsingActivationThrottle> throttle_;
+  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> throttle_task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(SubresourceFilterSafeBrowsingClient);
+};
+
+}  // namespace subresource_filter
+
+#endif  // COMPONENTS_SUBRESOURCE_FILTER_CONTENT_BROWSER_SUBRESOURCE_FILTER_SAFE_BROWSING_CLIENT_H_