toolbar.xml

 <android.support.design.widget.AppBarLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content">
                <android.support.v7.widget.Toolbar
                    android:id="@id/toolbar"
                    android:layout_width="match_parent"
                    android:layout_height="?attr/actionBarSize">
                    <ImageView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:src="@drawable/savyour_logo"
                        android:layout_gravity="center"
                        android:contentDescription="@string/content_description" />
                </android.support.v7.widget.Toolbar>
            </android.support.design.widget.AppBarLayout>