[Extensions] DCHECK that ExtensionFunctions respond (and only once)

extensions/browser/api/bluetooth/bluetooth_private_api.h

Index: extensions/browser/api/bluetooth/bluetooth_private_api.h
diff --git a/extensions/browser/api/bluetooth/bluetooth_private_api.h b/extensions/browser/api/bluetooth/bluetooth_private_api.h
index a35dc2ea54d0e288f50b9deaceaaf85f7deb0f1e..477d19a0a1172f8f78188daab548201186ea8d7d 100644
--- a/extensions/browser/api/bluetooth/bluetooth_private_api.h
+++ b/extensions/browser/api/bluetooth/bluetooth_private_api.h
@@ -75,6 +75,10 @@ class BluetoothPrivateSetAdapterStateFunction
   // Set of adapter properties that were not set successfully.
   std::set<std::string> failed_properties_;
 
+  // Whether or not the function has finished parsing the arguments and queuing
+  // up state requests.
+  bool parsed_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(BluetoothPrivateSetAdapterStateFunction);
 };