docs: remove outdated troubleshooting (microsoft#4706)

Most of the troubleshooting.md doc is not relevant any more:
- dependencies are maintained and helped with by launch doctor
- sandbox is disabled in Chromium by default

References microsoft#4683

Author: aslushnikov

docs/troubleshooting.md

@@ -1,187 +1,18 @@
 # Troubleshooting
 
 <!-- GEN:toc -->
-- [Chromium](#chromium)
-  * [Chrome headless doesn't launch on Windows](#chrome-headless-doesnt-launch-on-windows)
-  * [Chrome headless doesn't launch on Linux/WSL](#chrome-headless-doesnt-launch-on-linuxwsl)
-  * [Setting Up Chrome Linux Sandbox](#setting-up-chrome-linux-sandbox)
-- [Firefox](#firefox)
-  * [Firefox headless doesn't launch on Linux/WSL](#firefox-headless-doesnt-launch-on-linuxwsl)
-- [WebKit](#webkit)
-  * [WebKit headless doesn't launch on Linux/WSL](#webkit-headless-doesnt-launch-on-linuxwsl)
+- [Browser dependencies](#browser-dependencies)
 - [Code transpilation issues](#code-transpilation-issues)
 - [Node.js requirements](#nodejs-requirements)
   * [ReferenceError: URL is not defined](#referenceerror-url-is-not-defined)
 <!-- GEN:stop -->
 
-## Chromium
+## Browser dependencies
 
-### Chrome headless doesn't launch on Windows
+Playwright does self-inspection every time it runs to make sure the browsers can be launched successfully. If there are missing
+dependencies, playwright will print instructions to acquire them.
 
-Some [chrome policies](https://support.google.com/chrome/a/answer/7532015?hl=en) might enforce running Chrome/Chromium
-with certain extensions.
-
-Playwright passes `--disable-extensions` flag by default and will fail to launch when such policies are active.
-
-To work around this, try running without the flag:
-
-```js
-const browser = await playwright.chromium.launch({
-  ignoreDefaultArgs: ['--disable-extensions'],
-});
-```
-
-> Context: [Puppeteer#3681](https://github.com/puppeteer/puppeteer/issues/3681#issuecomment-447865342).
-
-### Chrome headless doesn't launch on Linux/WSL
-
-Make sure all the necessary dependencies are installed. You can run `ldd chrome | grep not` on a Linux
-machine to check which dependencies are missing. For dependencies on Ubuntu, please refer to [Dockerfile](https://github.com/microsoft/playwright/blob/master/docs/docker/Dockerfile.bionic) which is used to run our tests.
-
-The common ones for Debian and CentOS are provided below.
-
-<details>
-<summary>Debian (e.g. Ubuntu) Dependencies</summary>
-
-```
-gconf-service
-libasound2
-libatk1.0-0
-libatk-bridge2.0-0
-libc6
-libcairo2
-libcups2
-libdbus-1-3
-libexpat1
-libfontconfig1
-libgcc1
-libgconf-2-4
-libgdk-pixbuf2.0-0
-libglib2.0-0
-libgtk-3-0
-libnspr4
-libpango-1.0-0
-libpangocairo-1.0-0
-libstdc++6
-libx11-6
-libx11-xcb1
-libxcb1
-libxcomposite1
-libxcursor1
-libxdamage1
-libxext6
-libxfixes3
-libxi6
-libxrandr2
-libxrender1
-libxss1
-libxtst6
-ca-certificates
-fonts-liberation
-libappindicator1
-libnss3
-lsb-release
-xdg-utils
-wget
-libgbm1
-```
-</details>
-
-<details>
-<summary>CentOS Dependencies</summary>
-
-```
-pango.x86_64
-libXcomposite.x86_64
-libXcursor.x86_64
-libXdamage.x86_64
-libXext.x86_64
-libXi.x86_64
-libXtst.x86_64
-cups-libs.x86_64
-libXScrnSaver.x86_64
-libXrandr.x86_64
-GConf2.x86_64
-alsa-lib.x86_64
-atk.x86_64
-gtk3.x86_64
-ipa-gothic-fonts
-xorg-x11-fonts-100dpi
-xorg-x11-fonts-75dpi
-xorg-x11-utils
-xorg-x11-fonts-cyrillic
-xorg-x11-fonts-Type1
-xorg-x11-fonts-misc
-```
-
-After installing dependencies you need to update nss library using this command
-
-```
-yum update nss -y
-```
-</details>
-
-<details>
-  <summary>Check out discussions</summary>
-
-- [Puppeteer#290](https://github.com/puppeteer/puppeteer/issues/290) - Debian troubleshooting <br/>
-- [Puppeteer#391](https://github.com/puppeteer/puppeteer/issues/391) - CentOS troubleshooting <br/>
-- [Puppeteer#379](https://github.com/puppeteer/puppeteer/issues/379) - Alpine troubleshooting <br/>
-</details>
-
-Please file new issues in this repo for things relating to Playwright.
-
-### Setting Up Chrome Linux Sandbox
-
-In order to protect the host environment from untrusted web content, Chrome uses [multiple layers of sandboxing](https://chromium.googlesource.com/chromium/src/+/HEAD/docs/linux_sandboxing.md). For this to work properly,
-the host should be configured first. If there's no good sandbox for Chrome to use, it will crash
-with the error `No usable sandbox!`.
-
-If you **absolutely trust** the content you open in Chrome, you can launch Chrome
-with the `chromiumSandbox: false` option:
-
-```js
-const browser = await playwright.chromium.launch({ chromiumSandbox: false });
-```
-
-> **NOTE**: Running without a sandbox is **strongly discouraged**. Consider configuring a sandbox instead.
-
-To enable Chromium sandbox, you should enable [user namespace cloning](http://man7.org/linux/man-pages/man7/user_namespaces.7.html).
-
-User namespace cloning is only supported by modern kernels. Unprivileged user
-namespaces are generally fine to enable, but in some cases they open up more
-kernel attack surface for (unsandboxed) non-root processes to elevate to kernel
-privileges.
-
-In general, user namespace cloning can be enabled with the following command:
-
-```bash
-sudo sysctl -w kernel.unprivileged_userns_clone=1
-```
-
-In case of Docker, containers need to be run with a custom [security profile](https://docs.docker.com/engine/security/seccomp/) that enables
-user namespace cloning. You can download this profile here: [`seccomp_profile.json`](docker/seccomp_profile.json)
-
-With the downloaded profile, docker container could be run like this:
-
-```sh
-docker run --rm --security-opt seccomp=/path/to/seccomp/profile.json -it my-image-name
-```
-
-
-## Firefox
-
-### Firefox headless doesn't launch on Linux/WSL
-
-Make sure all the necessary dependencies are installed. You can run `ldd chrome | grep not` on a Linux
-machine to check which dependencies are missing. For dependencies on Ubuntu, please refer to [Dockerfile](https://github.com/microsoft/playwright/blob/master/docs/docker/Dockerfile.bionic) which is used to run our tests.
-
-## WebKit
-
-### WebKit headless doesn't launch on Linux/WSL
-
-Make sure all the necessary dependencies are installed. You can run `ldd chrome | grep not` on a Linux
-machine to check which dependencies are missing. For dependencies on Ubuntu, please refer to [Dockerfile](https://github.com/microsoft/playwright/blob/master/docs/docker/Dockerfile.bionic) which is used to run our tests.
+We also provide [Ubuntu 18.04 dockerfile](docker/Dockerfile.bionic) and [Ubuntu 20.04 dockerfile](docker/Dockerfile.focal) with the list of Debian dependencies.
 
 ## Code transpilation issues