Add support for passing an arbitrary parameter to an IPC message handler. The motivation is for Web…

content/browser/renderer_host/media/audio_renderer_host_unittest.cc

Index: content/browser/renderer_host/media/audio_renderer_host_unittest.cc
===================================================================
--- content/browser/renderer_host/media/audio_renderer_host_unittest.cc	(revision 270218)
+++ content/browser/renderer_host/media/audio_renderer_host_unittest.cc	(working copy)
@@ -89,9 +89,9 @@
     bool handled = true;
     IPC_BEGIN_MESSAGE_MAP(MockAudioRendererHost, *message)
       IPC_MESSAGE_HANDLER(AudioMsg_NotifyStreamCreated,
-                          OnStreamCreated)
+                          OnNotifyStreamCreated)
       IPC_MESSAGE_HANDLER(AudioMsg_NotifyStreamStateChanged,
-                          OnStreamStateChanged)
+                          OnNotifyStreamStateChanged)
       IPC_MESSAGE_UNHANDLED(handled = false)
     IPC_END_MESSAGE_MAP()
     EXPECT_TRUE(handled);
@@ -100,15 +100,14 @@
     return true;
   }
 
-  void OnStreamCreated(const IPC::Message& msg,
-                       int stream_id,
-                       base::SharedMemoryHandle handle,
+  void OnNotifyStreamCreated(int stream_id,
+                             base::SharedMemoryHandle handle,
 #if defined(OS_WIN)
-                       base::SyncSocket::Handle socket_handle,
+                             base::SyncSocket::Handle socket_handle,
 #else
-                       base::FileDescriptor socket_descriptor,
+                             base::FileDescriptor socket_descriptor,
 #endif
-                       uint32 length) {
+                             uint32 length) {
     // Maps the shared memory.
     shared_memory_.reset(new base::SharedMemory(handle, false));
     CHECK(shared_memory_->Map(length));
@@ -128,9 +127,8 @@
     OnStreamCreated(stream_id, length);
   }
 
-  void OnStreamStateChanged(const IPC::Message& msg,
-                            int stream_id,
-                            media::AudioOutputIPCDelegate::State state) {
+  void OnNotifyStreamStateChanged(int stream_id,
+                                  media::AudioOutputIPCDelegate::State state) {
     switch (state) {
       case media::AudioOutputIPCDelegate::kPlaying:
         OnStreamPlaying(stream_id);