[mojo-edk] Add support for transferring mach ports.

mojo/edk/embedder/embedder.h

Index: mojo/edk/embedder/embedder.h
diff --git a/mojo/edk/embedder/embedder.h b/mojo/edk/embedder/embedder.h
index 99191a97912a982ad36158b152bc4d5822bc30f3..17730719ade66490b012d7dcac4ba4720bc5141b 100644
--- a/mojo/edk/embedder/embedder.h
+++ b/mojo/edk/embedder/embedder.h
@@ -20,6 +20,10 @@
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/message_pipe.h"
 
+namespace base {
+class PortProvider;
+}
+
 namespace mojo {
 namespace edk {
 
@@ -134,6 +138,15 @@ MOJO_SYSTEM_IMPL_EXPORT void InitIPCSupport(
 // |OnShutdownComplete()| method is invoked.
 MOJO_SYSTEM_IMPL_EXPORT void ShutdownIPCSupport();
 
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+// Set the |base::PortProvider| for this process, if not already set. Can be
+// called on any thread, but must be set in the root process before any Mach
+// ports can be transferred. It is safe to call this multiple times, as long as
+// the same port provider is used every time.
+MOJO_SYSTEM_IMPL_EXPORT void SetMachPortProviderIfNeeded(
+    base::PortProvider* port_provider);
+#endif
+
 // Creates a message pipe over an arbitrary platform channel. The other end of
 // the channel must also be passed to this function. Either endpoint can be in
 // any process.