Squashed commit of the following:

commit 6234739e7b0bad1eba19e29ca09b9e25d87e3e68
Author: Peter Cai <peter@typeblog.net>
Date:   Tue Jul 2 15:48:07 2019 +0800

    FODCircleView: Refactor position / size / color configuration

    * Expose color as a configurable attribute so that it can be configured
      in device-specific overlays.
    * Fetch position and size directly from FOD HAL. These are all
      hardware-specific properties, and there is no need to rely on system
      properties.

    Change-Id: Ic4a33b27ab419e1e92e2af814f5088c972872098

commit 2994e7013fd0052e4ef4edbc1a6d86b1b518731a
Author: Peter Cai <peter@typeblog.net>
Date:   Mon Jul 1 19:03:13 2019 +0800

    FODCircleView: Move randomly to prevent burn-in

    * The FOD icon is always located on the same spot in Always-on Display
      mode. This poses a potential threat of burn-in since all devices with
      FOD are using OLED panels.
    * As a counter measure, we move the icon around just as how all the
      other elements in AOD move around. We set the maximum offset to 10% of
      the size of the icon so that it is within the margin of error for pretty
      much every possible sensor.

    Change-Id: I17204326d36e88425312f15cbc318bd01dda1e9c

commit 7868c9f0c6810369dbd8c2db4be9696928f7d0e9
Author: LuK1337 <priv.luk@gmail.com>
Date:   Sun Jun 30 15:42:46 2019 +0200

    FODCircleView: Support finger down/up callbacks from HAL

    * These are used when device is in AOD mode.

    Change-Id: Icb11072bc9759649d6453ee259756ae10357c37d

commit 2e27105607fad9851de62c8f31fcad268c27f8c7
Author: Peter Cai <peter@typeblog.net>
Date:   Fri Jun 28 20:52:42 2019 +0800

    FODCircleView: Support all screen orientations

    * When the screen is rotated, the FODCircleView has to move its
      on-screen coordinates in order to keep it always over the fingerprint
      scanner.

    Change-Id: I32a8114d3a7b24d355ff04ceda8abd3a08a7720a

commit 67e4bf0a3ec5e2499be487e3320dd339f1732000
Author: Peter Cai <peter@typeblog.net>
Date:   Fri Apr 5 16:44:18 2019 +0200

    Initial support for in-display fingerprint sensors

    Change-Id: I52beaf6492b9daa012b5d42b858d552d1e378a2c

Change-Id: I4c8fb53291ad084ee2cf50c125af857e50ab46bc

packages/SystemUI/res/drawable/fod_icon_default.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2019 The LineageOS 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.
+-->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="120dp"
+    android:height="120dp"
+    android:viewportWidth="100"
+    android:viewportHeight="100">
+    <path
+        android:fillColor="#bf7f7f7f"
+        android:fillType="evenOdd"
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+</vector>