Move IPC::MessageFilter and router to a separate file

components/tracing/child_trace_message_filter.h

Index: components/tracing/child_trace_message_filter.h
diff --git a/components/tracing/child_trace_message_filter.h b/components/tracing/child_trace_message_filter.h
index d2aae3b5257c67c27aaa3a467193065594ae6350..cc52418cec3ef756bebe438e7dca125226be2902 100644
--- a/components/tracing/child_trace_message_filter.h
+++ b/components/tracing/child_trace_message_filter.h
@@ -7,7 +7,7 @@
 
 #include "base/bind.h"
 #include "base/memory/ref_counted_memory.h"
-#include "ipc/ipc_channel_proxy.h"
+#include "ipc/message_filter.h"
 
 namespace base {
 class MessageLoopProxy;
@@ -16,11 +16,11 @@ class MessageLoopProxy;
 namespace tracing {
 
 // This class sends and receives trace messages on child processes.
-class ChildTraceMessageFilter : public IPC::ChannelProxy::MessageFilter {
+class ChildTraceMessageFilter : public IPC::MessageFilter {
  public:
   explicit ChildTraceMessageFilter(base::MessageLoopProxy* ipc_message_loop);
 
-  // IPC::ChannelProxy::MessageFilter implementation.
+  // IPC::MessageFilter implementation.
   virtual void OnFilterAdded(IPC::Channel* channel) OVERRIDE;
   virtual void OnFilterRemoved() OVERRIDE;
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;