Factor out the message sink from MockRenderThread to a separate class. I will...

chrome/common/ipc_test_sink.cc

+// Copyright (c) 2009 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.
+
+#include "chrome/common/ipc_test_sink.h"
+
+namespace IPC {
+
+TestSink::TestSink() {
+}
+
+TestSink::~TestSink() {
+}
+
+void TestSink::OnMessageReceived(const Message& msg) {
+  messages_.push_back(Message(msg));
+}
+
+void TestSink::ClearMessages() {
+  messages_.clear();
+}
+
+const Message* TestSink::GetMessageAt(size_t index) const {
+  if (index >= messages_.size())
+    return NULL;
+  return &messages_[index];
+}
+
+const Message* TestSink::GetFirstMessageMatching(uint16 id) const {
+  for (size_t i = 0; i < messages_.size(); i++) {
+    if (messages_[i].type() == id)
+      return &messages_[i];
+  }
+  return NULL;
+}
+
+const Message* TestSink::GetUniqueMessageMatching(uint16 id) const {
+  size_t found_index = 0;
+  size_t found_count = 0;
+  for (size_t i = 0; i < messages_.size(); i++) {
+    if (messages_[i].type() == id) {
+      found_count++;
+      found_index = i;
+    }
+  }
+  if (found_count != 1)
+    return NULL;  // Didn't find a unique one.
+  return &messages_[found_index];
+}
+
+}  // namespace IPC