Add a GUID to base::SharedMemoryHandle.

ppapi/proxy/nacl_message_scanner.cc

Index: ppapi/proxy/nacl_message_scanner.cc
diff --git a/ppapi/proxy/nacl_message_scanner.cc b/ppapi/proxy/nacl_message_scanner.cc
index 19edce26768e4ef656cec321ae7acdb3a71d1a6d..c098c6624aa75a3fc5a8711a74abcf4b45e1f936 100644
--- a/ppapi/proxy/nacl_message_scanner.cc
+++ b/ppapi/proxy/nacl_message_scanner.cc
@@ -59,9 +59,19 @@ void WriteHandle(int handle_index,
                  base::Pickle* msg) {
   SerializedHandle::WriteHeader(handle.header(), msg);
 
-  if (handle.type() != SerializedHandle::INVALID) {
+  if (handle.type() == SerializedHandle::SHARED_MEMORY) {
     // Now write the handle itself in POSIX style.
-    // See ParamTraits<FileDescriptor>::Read for where these values are read.
+    // This serialization must be kept in sync with
+    // ParamTraits<SharedMemoryHandle>::Write and
+    // ParamTraits<UnguessableToken>::Write.
+    msg->WriteBool(true);  // valid == true
+    msg->WriteInt(handle_index);
+    msg->WriteUInt64(handle.shmem().GetGUID().GetHighForSerialization());
+    msg->WriteUInt64(handle.shmem().GetGUID().GetLowForSerialization());
+  } else if (handle.type() != SerializedHandle::INVALID) {
+    // Now write the handle itself in POSIX style.
+    // This serialization must be kept in sync with
+    // ParamTraits<FileDescriptor>::Write.
     msg->WriteBool(true);  // valid == true
     msg->WriteInt(handle_index);
   }