Update action bar style in app header UI. am: be6fab0135

am: 00a0978293

Change-Id: I4d4029d732602dd515249d344e5edc597b858a54

res/drawable/action_bar_dropshadow.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Copyright (C) 2017 The Android Open Source Project
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+  -->
+
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+       android:shape="rectangle">
+    <gradient
+        android:angle="270"
+        android:startColor="#4D000000"
+        android:endColor="@android:color/transparent"
+        android:type="linear" />
+    <size android:height="8dp" />
+</shape>