builder.AddConnectionCallbacks(this); Not working

Hello I'm trying to use both

builder.AddConnectionCallbacks(this);

and

mGoogleSignIn.Click += mGoogleSignIn_Click;

However, mGoogleSignIn_Click are both giving me trouble.

builder.AddConnectionCallbacks(this); states it can't be inside of MainActivity due to (this) and mGoogleSignIn_Click states it does not exist in current context. I'm using Visual Studio 2015, Android App.

public class MainActivity : Activity
        {

            private Button mBtnSignUp;
            private ProgressBar mProgressBar;
            private GoogleApiClient mGoogleApiClient;
            private SignInButton mGoogleSignIn;
            protected override void OnCreate(Bundle bundle)
            {
                base.OnCreate(bundle);

                // Set our view from the "main" layout resource
                SetContentView(Resource.Layout.Main);

                mGoogleSignIn = FindViewById<SignInButton>(Resource.Id.sign_in_button);

                mGoogleSignIn.Click += mGoogleSignIn_Click;

                GoogleApiClient.Builder builder = new GoogleApiClient.Builder(this);

                builder.AddConnectionCallbacks(this);   

                mBtnSignUp = FindViewById<Button>(Resource.Id.btnSignUp);

                mProgressBar = FindViewById<ProgressBar>(Resource.Id.progressBar1);

                mBtnSignUp.Click += (object sender, EventArgs args) =>
                    {
                        //Pull up dialog
                        FragmentTransaction transaction = FragmentManager.BeginTransaction();
                        dialog_SignUp signUpDialog = new dialog_SignUp();
                        signUpDialog.Show(transaction, "dialog fragment");

                        signUpDialog.mOnSignUpComplete += signUpDialog_mOnSignUpComplete;
                    };
            }
            void mGoogleSighIn_Click(object sender, EventArgs e)
            {
                //Fire
            }