Add a way to implement GetInterface in the broker.

ppapi/proxy/proxy_channel.h

Index: ppapi/proxy/proxy_channel.h
diff --git a/ppapi/proxy/proxy_channel.h b/ppapi/proxy/proxy_channel.h
index 0a1fb0305a6509f6fec68e807a401fd3cc2facdf..f32d470425ad919d04c0608d2bcf9c01d89e1ab3 100644
--- a/ppapi/proxy/proxy_channel.h
+++ b/ppapi/proxy/proxy_channel.h
@@ -28,8 +28,6 @@ class PPAPI_PROXY_EXPORT ProxyChannel
     : public IPC::Channel::Listener,
       public IPC::Message::Sender {
  public:
-  typedef void (*ShutdownModuleFunc)();
-
   class PPAPI_PROXY_EXPORT Delegate {
    public:
     virtual ~Delegate() {}