Convert WriteMessage...() to use the new user pointer handling (see r285350).

mojo/system/message_in_transit.cc

Index: mojo/system/message_in_transit.cc
diff --git a/mojo/system/message_in_transit.cc b/mojo/system/message_in_transit.cc
index 944e12b19ae68b8613e30bb1020dc51f4915ff2e..5ac07547aac9c0c67336741dcb65b082a1808658 100644
--- a/mojo/system/message_in_transit.cc
+++ b/mojo/system/message_in_transit.cc
@@ -92,19 +92,7 @@ MessageInTransit::MessageInTransit(Type type,
     : main_buffer_size_(RoundUpMessageAlignment(sizeof(Header) + num_bytes)),
       main_buffer_(static_cast<char*>(base::AlignedAlloc(main_buffer_size_,
                                                          kMessageAlignment))) {
-  DCHECK_LE(num_bytes, kMaxMessageNumBytes);
-
-  // |total_size| is updated below, from the other values.
-  header()->type = type;
-  header()->subtype = subtype;
-  header()->source_id = kInvalidEndpointId;
-  header()->destination_id = kInvalidEndpointId;
-  header()->num_bytes = num_bytes;
-  header()->unused = 0;
-  // Note: If dispatchers are subsequently attached, then |total_size| will have
-  // to be adjusted.
-  UpdateTotalSize();
-
+  ConstructorHelper(type, subtype, num_bytes);
   if (bytes) {
     memcpy(MessageInTransit::bytes(), bytes, num_bytes);
     memset(static_cast<char*>(MessageInTransit::bytes()) + num_bytes, 0,
@@ -114,6 +102,17 @@ MessageInTransit::MessageInTransit(Type type,
   }
 }
 
+MessageInTransit::MessageInTransit(Type type,
+                                   Subtype subtype,
+                                   uint32_t num_bytes,
+                                   UserPointer<const void> bytes)
+    : main_buffer_size_(RoundUpMessageAlignment(sizeof(Header) + num_bytes)),
+      main_buffer_(static_cast<char*>(base::AlignedAlloc(main_buffer_size_,
+                                                         kMessageAlignment))) {
+  ConstructorHelper(type, subtype, num_bytes);
+  bytes.GetArray(MessageInTransit::bytes(), num_bytes);
+}
+
 MessageInTransit::MessageInTransit(const View& message_view)
     : main_buffer_size_(message_view.main_buffer_size()),
       main_buffer_(static_cast<char*>(base::AlignedAlloc(main_buffer_size_,
@@ -193,6 +192,23 @@ void MessageInTransit::SerializeAndCloseDispatchers(Channel* channel) {
   UpdateTotalSize();
 }
 
+void MessageInTransit::ConstructorHelper(Type type,
+                                         Subtype subtype,
+                                         uint32_t num_bytes) {
+  DCHECK_LE(num_bytes, kMaxMessageNumBytes);
+
+  // |total_size| is updated below, from the other values.
+  header()->type = type;
+  header()->subtype = subtype;
+  header()->source_id = kInvalidEndpointId;
+  header()->destination_id = kInvalidEndpointId;
+  header()->num_bytes = num_bytes;
+  header()->unused = 0;
+  // Note: If dispatchers are subsequently attached, then |total_size| will have
+  // to be adjusted.
+  UpdateTotalSize();
+}
+
 void MessageInTransit::UpdateTotalSize() {
   DCHECK_EQ(main_buffer_size_ % kMessageAlignment, 0u);
   header()->total_size = static_cast<uint32_t>(main_buffer_size_);