Put error_state into into it's own file.

base/error_state.cc

@@ -0,0 +1,19 @@
+#include "base/error_state.h"
+
+//----------------------------------------------------------------
+
+base::error_state
+base::combine_errors(error_state lhs, error_state rhs) {
+	switch (lhs) {
+	case NO_ERROR:
+		return rhs;
+
+	case NON_FATAL:
+		return (rhs == FATAL) ? FATAL : lhs;
+
+	default:
+		return lhs;
+	}
+}
+
+//----------------------------------------------------------------