Merge changes Id2732a94,Id8c01bf0

* changes:
  Adds a new activity for Gesture Navigation settings
  Adds BackGestureIndicatorView to animate left and right insets

res/layout/back_gesture_indicator_container.xml

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 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
+  -->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+              android:orientation="horizontal"
+              android:layout_width="match_parent"
+              android:layout_height="match_parent">
+
+    <ImageView
+        android:layout_width="@dimen/back_gesture_indicator_width"
+        android:layout_height="match_parent"
+        android:id="@+id/indicator_left">
+    </ImageView>
+
+    <Space
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        android:layout_weight="1" />
+
+    <ImageView
+        android:layout_width="@dimen/back_gesture_indicator_width"
+        android:layout_height="match_parent"
+        android:id="@+id/indicator_right">
+    </ImageView>
+
+</LinearLayout>
+