Add support for mapping node tree on the client.

mojo/services/view_manager/ids.h

Index: mojo/services/view_manager/ids.h
diff --git a/mojo/services/view_manager/ids.h b/mojo/services/view_manager/ids.h
index f599b5a09654a496f08b1dcc2bfb8974f956b52a..66efba39cb55f77207f6af5886cda7f52ecc7ccd 100644
--- a/mojo/services/view_manager/ids.h
+++ b/mojo/services/view_manager/ids.h
@@ -5,6 +5,7 @@
 #ifndef MOJO_SERVICES_VIEW_MANAGER_IDS_H_
 #define MOJO_SERVICES_VIEW_MANAGER_IDS_H_
 
+#include "mojo/services/public/cpp/view_manager/util.h"
 #include "mojo/services/public/cpp/view_manager/view_manager_types.h"
 #include "mojo/services/view_manager/view_manager_export.h"
 
@@ -55,16 +56,8 @@ struct MOJO_VIEW_MANAGER_EXPORT ViewId {
 };
 
 // Functions for converting to/from structs and transport values.
-inline uint16_t FirstIdFromTransportId(uint32_t id) {
-  return static_cast<uint16_t>((id >> 16) & 0xFFFF);
-}
-
-inline uint16_t SecondIdFromTransportId(uint32_t id) {
-  return static_cast<uint16_t>(id & 0xFFFF);
-}
-
 inline NodeId NodeIdFromTransportId(TransportNodeId id) {
-  return NodeId(FirstIdFromTransportId(id), SecondIdFromTransportId(id));
+  return NodeId(HiWord(id), LoWord(id));
 }
 
 inline TransportNodeId NodeIdToTransportId(const NodeId& id) {
@@ -72,7 +65,7 @@ inline TransportNodeId NodeIdToTransportId(const NodeId& id) {
 }
 
 inline ViewId ViewIdFromTransportId(TransportViewId id) {
-  return ViewId(FirstIdFromTransportId(id), SecondIdFromTransportId(id));
+  return ViewId(HiWord(id), LoWord(id));
 }
 
 inline TransportViewId ViewIdToTransportId(const ViewId& id) {