Adds a TransportDIB::Id value that is explicitly invalid and use it when compositing

content/common/common_param_traits.h

Index: content/common/common_param_traits.h
diff --git a/content/common/common_param_traits.h b/content/common/common_param_traits.h
index 8a099249ae109ac2d818e6887aa635f5a71b6c03..be65a2e4631bb4e42c56e8c6d588ded918b92825 100644
--- a/content/common/common_param_traits.h
+++ b/content/common/common_param_traits.h
@@ -383,6 +383,24 @@ struct ParamTraits<TransportDIB::Id> {
 };
 #endif
 
+#if defined(USE_X11)
+template<>
+struct ParamTraits<TransportDIB::Id> {
+  typedef TransportDIB::Id param_type;
+  static void Write(Message* m, const param_type& p) {
+    WriteParam(m, p.shmkey);
+  }
+  static bool Read(const Message* m, void** iter, param_type* r) {
+    return (ReadParam(m, iter, &r->shmkey));

[brettw, 2011/03/24 23:54:34]

I wouldn't do the extra parens around ReadParam.

+  }
+  static void Log(const param_type& p, std::string* l) {
+    l->append("TransportDIB(");
+    LogParam(p.shmkey, l);
+    l->append(")");
+  }
+};
+#endif
+
 template <>
 struct SimilarTypeTraits<WebKit::WebTextDirection> {
   typedef int Type;