Changing SpawnChild to return a struct.

mojo/public/c/system/platform_handle.h

Index: mojo/public/c/system/platform_handle.h
diff --git a/mojo/public/c/system/platform_handle.h b/mojo/public/c/system/platform_handle.h
index 0b02357d46a53ce49d32ef2aa4cad24871aa523c..69274c30c68b0226a69ae9509ee6fcc9d0f9b553 100644
--- a/mojo/public/c/system/platform_handle.h
+++ b/mojo/public/c/system/platform_handle.h
@@ -38,11 +38,14 @@ const MojoPlatformHandleType MOJO_PLATFORM_HANDLE_TYPE_INVALID = 0;
 const MojoPlatformHandleType MOJO_PLATFORM_HANDLE_TYPE_FILE_DESCRIPTOR = 1;
 const MojoPlatformHandleType MOJO_PLATFORM_HANDLE_TYPE_MACH_PORT = 2;
 const MojoPlatformHandleType MOJO_PLATFORM_HANDLE_TYPE_WINDOWS_HANDLE = 3;
+const MojoPlatformHandleType MOJO_PLATFORM_HANDLE_TYPE_PARCELABLE = 4;
 #else
 #define MOJO_PLATFORM_HANDLE_TYPE_INVALID ((MojoPlatformHandleType)0)
 #define MOJO_PLATFORM_HANDLE_TYPE_FILE_DESCRIPTOR ((MojoPlatformHandleType)1)
 #define MOJO_PLATFORM_HANDLE_TYPE_MACH_PORT ((MojoPlatformHandleType)2)
 #define MOJO_PLATFORM_HANDLE_TYPE_WINDOWS_HANDLE ((MojoPlatformHandleType)3)
+#define MOJO_PLATFORM_HANDLE_TYPE_PARCELABLE ((MojoPlatformHandleType)4)
+
 #endif
 
 // |MojoPlatformHandle|: A handle to an OS object.