|Seems like the other thread has a miscommunication.
Your current app has the credential information in the client code. The type of credential information is irrelevant.
The credential information is hard-coded because you stated that. (That means every actual user of the client will be using the same exact credentials.)
So the other solution is to modify the code to do the following
1. Create a server API method that expects a requests from the client code. The client code does NOT make a call to google. The client code does not have the credentials.
2. The server code API uses the credentials and makes the call to google.
3. The server code returns the result of the google code to the client.
Note in the above that I did not specify where the server code gets the credentials from. Could be it still hard-coded but in the server code. There are other possible solutions to providing the credentials to the server code.