app/src/main/res/layout/activity_google_sign_in.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/googleSignIn_activity"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".auth.GoogleSignInActivity">
<com.google.android.gms.common.SignInButton
android:id="@+id/googleBtn"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="166dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="353dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</com.google.android.gms.common.SignInButton>
</android.support.constraint.ConstraintLayout>