[Extensions Bindings] Add APIBindingsSystem

extensions/renderer/api_binding.h

Index: extensions/renderer/api_binding.h
diff --git a/extensions/renderer/api_binding.h b/extensions/renderer/api_binding.h
index fd3501b71afabd1431eebeb82172c988b4e2df27..a1f8706603d89dbf29799d2331eeb1130292fbe2 100644
--- a/extensions/renderer/api_binding.h
+++ b/extensions/renderer/api_binding.h
@@ -50,9 +50,10 @@ class APIBinding {
   using HandlerCallback = base::Callback<void(gin::Arguments*)>;
 
   // The ArgumentSpec::RefMap is required to outlive this object.
+  // |type_definitions| may be null if the API does not specify any types.
   APIBinding(const std::string& name,
              const base::ListValue& function_definitions,
-             const base::ListValue& type_definitions,
+             const base::ListValue* type_definitions,
              const APIMethodCallback& callback,
              ArgumentSpec::RefMap* type_refs);
   ~APIBinding();
@@ -80,6 +81,9 @@ class APIBinding {
                   const APISignature* signature,
                   gin::Arguments* args);
 
+  // The root name of the API, e.g. "tabs" for chrome.tabs.
+  std::string api_name_;
+
   // A map from method name to expected signature.
   std::map<std::string, std::unique_ptr<APISignature>> signatures_;