开发笔记:如何删除LinearLayout阴影？[重复]

我有以下布局：

XML code:


<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_
android:layout_
tools:cOntext=".Activities.OwnerProfileActivity">
android:id="@+id/linear_layout_profile_top"
android:layout_
android:layout_
android:background="@color/colorPrimary"
android:orientation="vertical"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
android:layout_
android:layout_ />
android:id="@+id/imageView_profile_picture"

android:layout_
app:srcCompat="@drawable/ic_user" />
android:id="@+id/textView_user_name"

android:layout_
android:layout_
android:text="TextView"
android:textSize="18sp" />

android:id="@+id/tabLayout"
android:layout_
android:layout_
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/linear_layout_profile_top"
app:tabSelectedTextColor="@color/colorPrimary">
android:layout_
android:layout_
android:text="@string/about_label" />
android:layout_
android:layout_
android:text="@string/businesses_label" />
android:layout_
android:layout_
android:text="@string/coupons_label" />

android:id="@+id/viewpager_page"
android:layout_
android:layout_
android:layout_marginTop="8dp"
app:layout_constraintBottom_toTopOf="@+id/lower_navigation"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/tabLayout"
app:layout_constraintVertical_bias="1.0" />
android:id="@+id/lower_navigation"
android:name="com.nprogramming.android.couponsapp.Fragments.LowerNavigationBarFragment"
android:layout_
android:layout_
app:layout_constraintBottom_toBottomOf="parent" />



如何删除ActionBar和LinearLayout（红色块）之间的阴影？

提前致谢。