Adds BackGestureIndicatorView to animate left and right insets

Bug: 146004827
Test: make RunSettingsRoboTests ROBOTEST_FILTER=BackGestureIndicatorViewTest

Change-Id: Id8c01bf047138a1721237f368f269c6def964515

tests/robotests/src/com/android/settings/gestures/BackGestureIndicatorViewTest.java

@@ -0,0 +1,64 @@
+/*
+ * 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.
+ */
+
+package com.android.settings.gestures;
+
+import static org.junit.Assert.assertEquals;
+
+import android.content.Context;
+import android.widget.ImageView;
+
+import com.android.settings.R;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+
+@RunWith(RobolectricTestRunner.class)
+public class BackGestureIndicatorViewTest {
+
+    private Context mContext;
+
+    private BackGestureIndicatorDrawable mLeftDrawable;
+    private BackGestureIndicatorDrawable mRightDrawable;
+
+    private BackGestureIndicatorView mView;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+
+        mContext = RuntimeEnvironment.application;
+        mView = new BackGestureIndicatorView(mContext);
+
+        mLeftDrawable = (BackGestureIndicatorDrawable) ((ImageView) mView.findViewById(
+                R.id.indicator_left)).getDrawable();
+        mRightDrawable = (BackGestureIndicatorDrawable) ((ImageView) mView.findViewById(
+                R.id.indicator_right)).getDrawable();
+    }
+
+    @Test
+    public void testSetIndicatoreWidth() {
+        mView.setIndicatorWidth(25, true);
+        mView.setIndicatorWidth(52, false);
+
+        assertEquals(25, mLeftDrawable.getWidth());
+        assertEquals(52, mRightDrawable.getWidth());
+    }
+}