[mojo] Allow value deserialization to fail

mojo/public/cpp/bindings/lib/string_serialization.cc

Index: mojo/public/cpp/bindings/lib/string_serialization.cc
diff --git a/mojo/public/cpp/bindings/lib/string_serialization.cc b/mojo/public/cpp/bindings/lib/string_serialization.cc
index be1508d425ceceadfa3e5eb70ff7f0ca182531a8..936493edffbd9bb6d495cb54ffaccbdf69fc57ee 100644
--- a/mojo/public/cpp/bindings/lib/string_serialization.cc
+++ b/mojo/public/cpp/bindings/lib/string_serialization.cc
@@ -28,7 +28,7 @@ void Serialize_(const String& input,
   }
 }
 
-void Deserialize_(internal::String_Data* input,
+bool Deserialize_(internal::String_Data* input,
                   String* output,
                   internal::SerializationContext* context) {
   if (input) {
@@ -37,6 +37,7 @@ void Deserialize_(internal::String_Data* input,
   } else {
     output->reset();
   }
+  return true;
 }
 
 }  // namespace mojo