Mojo: (Theoretically) implement the read side of platform handle passing.

mojo/embedder/platform_channel_utils_posix.h

Index: mojo/embedder/platform_channel_utils_posix.h
diff --git a/mojo/embedder/platform_channel_utils_posix.h b/mojo/embedder/platform_channel_utils_posix.h
index 6cfb988f8dc507df7c8c394012049629997b0507..9b23f2cab6c3cb842df54b9e07b953c8138bd501 100644
--- a/mojo/embedder/platform_channel_utils_posix.h
+++ b/mojo/embedder/platform_channel_utils_posix.h
@@ -12,6 +12,7 @@
 
 #include "base/memory/scoped_ptr.h"
 #include "mojo/embedder/platform_handle.h"
+#include "mojo/embedder/platform_handle_vector.h"
 #include "mojo/system/system_impl_export.h"
 
 struct iovec;  // Declared in <sys/uio.h>.
@@ -25,8 +26,6 @@ namespace embedder {
 // |FileDescriptorSet::kMaxDescriptorsPerMessage|. Where does it come from?
 const size_t kPlatformChannelMaxNumHandles = 7;
 
-typedef std::vector<PlatformHandle> PlatformHandleVector;
-
 // Use these to write to a socket created using |PlatformChannelPair| (or
 // equivalent). These are like |write()| and |writev()|, but handle |EINTR| and
 // never raise |SIGPIPE|. (Note: On Mac, the suppression of |SIGPIPE| is set up