Give generatored bindings classes a field remembering an index into a cache of handles on the corre…

tools/dom/scripts/systemnative.py

Index: tools/dom/scripts/systemnative.py
diff --git a/tools/dom/scripts/systemnative.py b/tools/dom/scripts/systemnative.py
index d36e0cd6b79e6a3ab0e805db66792421e55c15e0..21d5297c101b526e1d6e123de76e7322e76a84f9 100644
--- a/tools/dom/scripts/systemnative.py
+++ b/tools/dom/scripts/systemnative.py
@@ -129,10 +129,11 @@ def _GetCPPTypeName(interface_name, callback_name, cpp_name):
 class DartiumBackend(HtmlDartGenerator):
   """Generates Dart implementation for one DOM IDL interface."""
 
-  def __init__(self, interface, cpp_library_emitter, options):
+  def __init__(self, interface, cid, cpp_library_emitter, options):
     super(DartiumBackend, self).__init__(interface, options)
 
     self._interface = interface
+    self._cid = cid;
     self._cpp_library_emitter = cpp_library_emitter
     self._database = options.database
     self._template_loader = options.templates
@@ -357,6 +358,7 @@ class DartiumBackend(HtmlDartGenerator):
     self._cpp_impl_emitter.Emit(
         self._template_loader.Load('cpp_implementation.template'),
         INTERFACE=self._interface.id,
+        CID=str(self._cid),
         INCLUDES=self._GenerateCPPIncludes(self._cpp_impl_includes),
         CALLBACKS=self._cpp_definitions_emitter.Fragments(),
         RESOLVER=self._cpp_resolver_emitter.Fragments(),