[Extensions Bindings] Add a bridge to use current custom bindings

extensions/renderer/api_binding_hooks.h

Index: extensions/renderer/api_binding_hooks.h
diff --git a/extensions/renderer/api_binding_hooks.h b/extensions/renderer/api_binding_hooks.h
index 587425f427470b62b9370f103ededcb32619f69c..9c746214ccb1763658f3a38c628f0a642ad1a226 100644
--- a/extensions/renderer/api_binding_hooks.h
+++ b/extensions/renderer/api_binding_hooks.h
@@ -63,6 +63,10 @@ class APIBindingHooks {
                      const APISignature* signature,
                      gin::Arguments* arguments);
 
+  // Returns a JS interface that can be used to register hooks.
+  v8::Local<v8::Object> GetJSHookInterface(const std::string& api_name,
+                                           v8::Local<v8::Context> context);
+
  private:
   // Whether we've tried to use any hooks associated with this object.
   bool hooks_used_ = false;