Added details for Unity 2019 (add missing packages through the package manager) in README.md

Author: kidavid

README.md

@@ -21,7 +21,7 @@ today.
 
 [<img alt="Get ARCore Depth Lab on Google Play" height="50px" src="https://play.google.com/intl/en_us/badges/images/apps/en-play-badge-border.png" />](https://play.google.com/store/apps/details?id=com.google.ar.unity.arcore_depth_lab)
 
-## Sample Features
+## Sample features
 
 The sample scenes demonstrate three different ways to access depth:
 
@@ -45,17 +45,26 @@ coordinates (CPU).
   * Environment relighting
   * False-color depth map
 
-## Building and Running Samples
-These samples target [Unity 2018.4.16f1](https://unity3d.com) and require
-[ARCore SDK for Unity](https://github.com/google-ar/arcore-unity-sdk) v1.18.0 or
-newer. Download and import
+## Unity project setup
+These samples target [**Unity 2018.4.16f1**](https://unity3d.com) and require
+[**ARCore SDK for Unity**](https://github.com/google-ar/arcore-unity-sdk)
+**v1.18.0** or newer. Download and import
 [`arcore-unity-sdk-1.18.0.unitypackage`](https://github.com/google-ar/arcore-unity-sdk/releases)
 or newer into the sample project. Close and reopen the project and reimport all
 demo shaders to resolve any dependency issues in the Unity editor. This project
 only builds with the Build Platform **Android**. **Instant Preview** is not
 enabled for Depth API yet. Build the project to an Android device instead of
 using the **Play** button in the Unity editor.
 
+In **Unity 2019 or newer** you may see code errors associated with
+`SpatialTracking`, `NetworkBehaviour`, and scripts in
+`Assets/GoogleARCore/*`. In `Unity > Window > Package Manager` add the following
+packages to resolve the issue:
+
+* **Multiplayer HLAPI** (com.unity.multiplayer-hlapi)
+* **XR Legacy Input Helpers** (com.unity.xr.legacyinputhelpers)
+
+## Building samples
 Individual scenes can be built and run by just enabling a particular scene, e.g.
 `FogEffect` to try out the depth-aware fog filter.
 
@@ -81,7 +90,7 @@ Assets/ARRealismDemos/DepthEffects/Scenes/DepthOfFieldEffect.unity
 Assets/ARRealismDemos/CollisionDetection/Scenes/CollisionAwareObjectPlacement.unity
 Assets/ARRealismDemos/Water/Scenes/Water.unity`
 
-## Upcoming breaking change affecting previously published 32-bit-only apps
+## Upcoming breaking change affecting 32-bit-only apps
 
 The project is set up to use the `IL2CPP` scripting backend instead of `Mono` to
 build an `ARM64` app. You may be prompted to locate the Android NDK folder.
@@ -101,7 +110,7 @@ may crash when attempting to start an augmented reality (AR) session.
 To learn more about this breaking change, and for instructions on how to update
 your app, see https://developers.google.com/ar/64bit.
 
-## Sample Project Structure
+## Sample project structure
 
 The main sample assets are placed inside the `Assets/ARRealismDemos` folder.
 Each subfolder contains sample features or helper components.
@@ -203,7 +212,7 @@ environment.
 This sample uses a modified GPU occlusion shader to create a
 flooding effect with artificial water in the physical environment.
 
-## Developing your own ARCore Depth-enabled Unity Experiences
+## Developing your own ARCore Depth-enabled Unity experiences
 Please make sure that the Unity scene is properly set up to run ARCore. Provide
 depth data by attaching the `ARCoreSession` to the appropriate configuration.
 Please see the example provided in the
@@ -224,7 +233,7 @@ customized in the editor when `DepthSource` is explicitly placed in the scene.
 the `DepthTarget` script is attached to a `GameObject` with a `Meshrenderer`
 component.
 
-## Helper Classes
+## Helper classes
 
 ### `DepthSource`
 A singleton instance of this class contains references to the CPU array and GPU
@@ -242,7 +251,7 @@ scene in order for `DepthSource` to provide depth data.
 This class contains low-level operations and access to the depth data. It should
 only be use by advanced developers.
 
-## User Privacy Requirements
+## User privacy requirements
 
 You must prominently disclose the use of Google Play Services for AR (ARCore)
 and how it collects and processes data in your application. This information
@@ -266,7 +275,7 @@ If you use ARCore Depth Lab in your research, please reference it as:
       series = {UIST},
     }
 
-## Additional Information
+## Additional information
 
 You may use this software under the
 [Apache 2.0 License](https://github.com/googlesamples/arcore-depth-lab/blob/master/LICENSE).