Add support for sending protobuf messages over IPC.

chrome/common/safe_browsing/protobuf_message_param_traits.h

+// Copyright 2015 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 CHROME_COMMON_SAFE_BROWSING_PROTOBUF_MESSAGE_PARAM_TRAITS_H_
+#define CHROME_COMMON_SAFE_BROWSING_PROTOBUF_MESSAGE_PARAM_TRAITS_H_
+
+#include <string>
+
+#include "base/pickle.h"
+#include "ipc/ipc_message.h"
+#include "ipc/ipc_param_traits.h"
+#include "third_party/protobuf/src/google/protobuf/repeated_field.h"
+
+namespace IPC {
+
+template <class Element>
+struct ParamTraits<google::protobuf::RepeatedPtrField<Element>> {
+  typedef google::protobuf::RepeatedPtrField<Element> param_type;
+
+  static void Write(Message* m, const param_type& p) {
+    WriteParam(m, p.size());
+    for (const auto& element : p)
+      WriteParam(m, element);
+  }
+
+  static bool Read(const Message* m, PickleIterator* iter, param_type* p) {
+    int size;
+    if (!iter->ReadLength(&size) || size < 0)
+      return false;
+    if (INT_MAX / static_cast<int>(sizeof(void*)) <= size)
+      return false;
+    p->Clear();
+    p->Reserve(size);
+    while (size--) {
+      if (!ReadParam(m, iter, p->Add()))
+        return false;
+    }
+    return true;
+  }
+
+  static void Log(const param_type& p, std::string* l) {
+    bool logged_first = false;
+    for (const auto& element : p) {
+      if (logged_first)
+        l->push_back(' ');
+      else
+        logged_first = true;
+      LogParam(element, l);
+    }
+  }
+};
+
+}  // namespace IPC
+
+#endif  // CHROME_COMMON_SAFE_BROWSING_PROTOBUF_MESSAGE_PARAM_TRAITS_H_