Move IPC::MessageFilter and router to a separate file

content/renderer/p2p/socket_dispatcher.h

Index: content/renderer/p2p/socket_dispatcher.h
diff --git a/content/renderer/p2p/socket_dispatcher.h b/content/renderer/p2p/socket_dispatcher.h
index 5709e93b6301eb7cc1af0af8fd8c7d6565f92f2c..5bfd264d213d1aaa64c67f3ea4225c9700f6aec7 100644
--- a/content/renderer/p2p/socket_dispatcher.h
+++ b/content/renderer/p2p/socket_dispatcher.h
@@ -30,7 +30,7 @@
 #include "base/synchronization/lock.h"
 #include "content/common/content_export.h"
 #include "content/common/p2p_socket_type.h"
-#include "ipc/ipc_channel_proxy.h"
+#include "ipc/message_filter.h"
 #include "net/base/net_util.h"
 
 namespace base {
@@ -48,8 +48,7 @@ class P2PAsyncAddressResolver;
 class P2PSocketClientImpl;
 class RenderViewImpl;
 
-class CONTENT_EXPORT P2PSocketDispatcher
-    : public IPC::ChannelProxy::MessageFilter {
+class CONTENT_EXPORT P2PSocketDispatcher : public IPC::MessageFilter {
  public:
   explicit P2PSocketDispatcher(base::MessageLoopProxy* ipc_message_loop);
 
@@ -73,7 +72,7 @@ class CONTENT_EXPORT P2PSocketDispatcher
   // Send a message asynchronously.
   virtual void Send(IPC::Message* message);
 
-  // IPC::ChannelProxy::MessageFilter override. Called on IO thread.
+  // IPC::MessageFilter override. Called on IO thread.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   virtual void OnFilterAdded(IPC::Channel* channel) OVERRIDE;
   virtual void OnFilterRemoved() OVERRIDE;