Add support for attaching filters to an IPC TestSink.

ipc/ipc_test_sink.h

Index: ipc/ipc_test_sink.h
diff --git a/ipc/ipc_test_sink.h b/ipc/ipc_test_sink.h
index c6114f166821de69e8563125a5d76e083c62b49b..3acb3dc8c8f5a812e8a63f10c10245bdf84dc4de 100644
--- a/ipc/ipc_test_sink.h
+++ b/ipc/ipc_test_sink.h
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/observer_list.h"
 #include "ipc/ipc_channel.h"
 
 namespace IPC {
@@ -41,10 +42,39 @@ class Message;
 //   // Go on to the next phase of the test.
 //   test_sink.ClearMessages();
 //
+// You can also register to be notified when messages are posted to the sink.
+// This can be useful if you need to wait for a particular message that will
+// be posted asynchronously.  Example usage:
+//
+//   class MyObserver : public IPC::TestSink::Observer {
+//     public:

[noelutz, 2011/01/28 02:13:06]

nit: indentation is wrong I think.

[Brian Ryner, 2011/01/28 20:43:07]

Done.

+//       virtual void OnMessageReceived(const IPC::Message& msg) {
+//         <do something with the message>
+//         MessageLoop::current()->Quit();
+//       }
+//   };
+//
+//   MyObserver observer;
+//   test_sink.AddObserver(&observer);
+//   StartSomeAsynchronousProcess(&test_sink);
+//   MessageLoop::current()->Run();
+//   <inspect the results>
+//   ...
+//
 // To hook up the sink, all you need to do is call OnMessageReceived when a
 // message is received.
 class TestSink : public Channel {
  public:
+  // Callers can register as an observer to be notified for each message
+  // that is sent to the TestSink.
+  class Observer {
+   public:
+    virtual ~Observer() {}
+
+    // OnMessageReceived is called after each message is added to the TestSink.
+    virtual void OnMessageReceived(const Message& msg) = 0;
+  };
+
   TestSink();
   ~TestSink();
 
@@ -79,9 +109,16 @@ class TestSink : public Channel {
   // or the list is cleared.
   const Message* GetUniqueMessageMatching(uint32 id) const;
 
+  // Adds the given observer to the TestSink.
+  void AddObserver(Observer* obs);
+
+  // Removes the given observer from the TestSink.
+  void RemoveObserver(Observer* obs);
+
  private:
   // The actual list of received messages.
   std::vector<Message> messages_;
+  ObserverList<Observer> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(TestSink);
 };