EDK: Move {platform_handle,scoped_platform_handle}.* to //mojo/edk/platform.

mojo/edk/system/data_pipe.cc

Index: mojo/edk/system/data_pipe.cc
diff --git a/mojo/edk/system/data_pipe.cc b/mojo/edk/system/data_pipe.cc
index d3863dfb3241e7e3aed2471b09645f3e93bab0fa..f6830b66d42b32579b35e056010d5cc0e7bef6be 100644
--- a/mojo/edk/system/data_pipe.cc
+++ b/mojo/edk/system/data_pipe.cc
@@ -25,7 +25,7 @@
 #include "mojo/edk/system/remote_producer_data_pipe_impl.h"
 #include "mojo/edk/util/make_unique.h"
 
-using mojo::embedder::ScopedPlatformHandle;
+using mojo::platform::ScopedPlatformHandle;
 using mojo::util::MakeUnique;
 using mojo::util::MutexLocker;
 using mojo::util::RefPtr;