[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..040613fffd31e2ba8f47a8fef3af94ddf572572b 100644
--- a/extensions/renderer/api_binding.h
+++ b/extensions/renderer/api_binding.h
@@ -80,6 +80,9 @@ 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_;