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

chrome/common/ipc_test_sink.h

Index: chrome/common/ipc_test_sink.h
===================================================================
--- chrome/common/ipc_test_sink.h	(revision 0)
+++ chrome/common/ipc_test_sink.h	(revision 0)
@@ -0,0 +1,76 @@
+// 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.
+
+#ifndef CHROME_COMMON_IPC_TEST_SINK_H_
+#define CHROME_COMMON_IPC_TEST_SINK_H_
+
+#include <utility>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "chrome/common/ipc_message.h"
+
+namespace IPC {
+
+// This test sink provides a "sink" for IPC messages that are sent. It allows
+// the caller to query messages received in various different ways.  It is
+// designed for tests for objects that use the IPC system.
+//
+// Typical usage:
+//
+//   test_sink.ClearMessages();
+//   do_something();
+//
+//   // We should have gotten exactly one update state message.
+//   EXPECT_TRUE(test_sink.GetUniqeMessageMatching(ViewHostMsg_Update::ID));
+//   // ...and no start load messages.
+//   EXPECT_FALSE(test_sink.GetFirstMessageMatching(ViewHostMsg_Start::ID));
+//
+//   // Go on to the next phase of the test.
+//   test_sink.ClearMessages();
+//
+// To hook up the sink, all you need to do is call OnMessageReceived when a
+// message is recieved.
+class TestSink {
+ public:
+  TestSink();
+  ~TestSink();
+
+  // Used by the source of the messages to send the message to the sink. This
+  // will make a copy of the message and store it in the list.
+  void OnMessageReceived(const Message& msg);
+
+  // Returns the number of messages in the queue.
+  size_t message_count() const { return messages_.size(); }
+
+  // Clears the message queue of saved messages.
+  void ClearMessages();
+
+  // Returns the message at the given index in the queue. The index may be out
+  // of range, in which case the return value is NULL. The returned pointer will
+  // only be valid until another message is received or the list is cleared.
+  const Message* GetMessageAt(size_t index) const;
+
+  // Returns the first message with the given ID in the queue. If there is no
+  // message with the given ID, returns NULL. The returned pointer will only be
+  // valid until another message is received or the list is cleared.
+  const Message* GetFirstMessageMatching(uint16 id) const;
+
+  // Returns the message with the given ID in the queue. If there is no such
+  // message or there is more than one of that message, this will return NULL
+  // (with the expectation that you'll do an ASSERT_TRUE() on the result).
+  // The returned pointer will only be valid until another message is received
+  // or the list is cleared.
+  const Message* GetUniqueMessageMatching(uint16 id) const;
+
+ private:
+  // The actual list of received messages.
+  std::vector<Message> messages_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestSink);
+};
+
+}  // namespace IPC
+
+#endif  // CHROME_COMMON_IPC_TEST_SINK_H_