EDK: Remove MOJO_SYSTEM_IMPL_EXPORT, system_impl_export.h, etc.

mojo/edk/system/proxy_message_pipe_endpoint.h

Index: mojo/edk/system/proxy_message_pipe_endpoint.h
diff --git a/mojo/edk/system/proxy_message_pipe_endpoint.h b/mojo/edk/system/proxy_message_pipe_endpoint.h
index c61fdb2e81401095f755b14706f208b3ee6f0c3d..b11093e43d8614aff61290ac8e0472700fec4b6a 100644
--- a/mojo/edk/system/proxy_message_pipe_endpoint.h
+++ b/mojo/edk/system/proxy_message_pipe_endpoint.h
@@ -8,7 +8,6 @@
 #include "base/memory/ref_counted.h"
 #include "mojo/edk/system/message_in_transit.h"
 #include "mojo/edk/system/message_pipe_endpoint.h"
-#include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
@@ -27,8 +26,7 @@ class MessagePipe;
 // remote consists of a |LocalMessagePipeEndpoint| and a
 // |ProxyMessagePipeEndpoint|, with only the local endpoint being accessible via
 // a |MessagePipeDispatcher|.
-class MOJO_SYSTEM_IMPL_EXPORT ProxyMessagePipeEndpoint final
-    : public MessagePipeEndpoint {
+class ProxyMessagePipeEndpoint final : public MessagePipeEndpoint {
  public:
   explicit ProxyMessagePipeEndpoint(ChannelEndpoint* channel_endpoint);
   ~ProxyMessagePipeEndpoint() override;