Add RoutingIDIssuer to ensure the correctness of ID to be routed.

content/browser/renderer_host/routing_id_issuer.h

Index: content/browser/renderer_host/routing_id_issuer.h
diff --git a/content/browser/renderer_host/routing_id_issuer.h b/content/browser/renderer_host/routing_id_issuer.h
new file mode 100644
index 0000000000000000000000000000000000000000..73f3ce3f373a378b4698abcf36bd1c5a08657302
--- /dev/null
+++ b/content/browser/renderer_host/routing_id_issuer.h
@@ -0,0 +1,44 @@
+// Copyright 2014 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_RENDERER_HOST_ROUTING_ID_ISSUER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_ROUTING_ID_ISSUER_H_
+
+#include "base/atomic_sequence_num.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
+#include "content/common/content_export.h"
+#include "ipc/ipc_message.h"
+
+namespace content {
+
+// A debug facility for tightening the routing ID usage across multiple
+// RenderProcessHost. The tracked ID is used by RenderProcessHost
+// to verify if the given ID is correct.
+class CONTENT_EXPORT RoutingIDIssuer {
+ public:
+  static scoped_ptr<RoutingIDIssuer> Create();
+  static scoped_ptr<RoutingIDIssuer> CreateWithMangler(int mangler);
+
+  int IssueNext();
+  bool IsProbablyValid(int issued_id) const;
+
+ private:
+  friend class RoutingIDManglingDisabler;
+
+  static void StartDisablingIDMangling();

[nasko, 2014/10/13 21:04:01]

nit: Those will be more readable if they are "Enable/Disable" instead of
"Start/StopDisabling".

[Hajime Morrita, 2014/10/13 22:23:54]

Done.

+  static void StopDisablingIDMangling();
+
+  explicit RoutingIDIssuer(int mangler);
+
+  base::AtomicSequenceNumber next_;
+  const int mangler_;
+
+  DISALLOW_COPY_AND_ASSIGN(RoutingIDIssuer);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_ROUTING_ID_ISSUER_H_