Ozone documentation: Take into account recent changes in Linux Desktop

docs/ozone_overview.md

 # Ozone Overview
 
 Ozone is a platform abstraction layer beneath the Aura window system that is
 used for low level input and graphics. Once complete, the abstraction will
 support underlying systems ranging from embedded SoC targets to new
 X11-alternative window systems on Linux such as Wayland or Mir to bring up Aura
 Chromium by providing an implementation of the platform interface.
 
 ## Guiding Principles
 
@@ skipping 142 matching lines @@
 ```
 
 Then to run for example the headless platform:
 
 ``` shell
 ./out/OzoneEmbedded/content_shell --disable-setuid-sandbox \
                                   --ozone-platform=headless \
                                   --ozone-dump-file=/tmp/
 ```
 
-### Linux Desktop - ([bug](http://crbug.com/295089))
+### Linux Desktop - ([waterfall](https://build.chromium.org/p/chromium.fyi/builders/Ozone%20Linux/))
+Support for Linux Desktop is currently [in-progress](http://crbug.com/295089).
 
-This is not supported by any of the in-tree platforms. Please see above and try
-a ChromeOS or embedded build for now.
+The following targets are currently working:
+
+* various unit tests
+* `content_shell`

[tonikitoo, 2016/11/08 13:09:21]

lets omit content_shell for now, since it is build-able but non-functional at
this point.

[fwang, 2016/11/08 13:12:18]

OK

+* `chrome`
+
+To build `chrome`, do this from the `src` directory:
+
+``` shell
+gn args out/OzoneLinuxDesktop --args="use_ozone=true enable_package_mash_services=true"
+ninja -C out/OzoneLinuxDesktop chrome
+```
+Then to run for example the X11 platform:
+
+``` shell
+./out/OzoneLinuxDesktop/chrome --ozone-platform=x11 \
+                               --disable-setuid-sandbox \
+                               --mash
+```
+
+Note: You may need to apply [this patch](https://codereview.chromium.org/2485673002/) to avoid missing ash resources during chrome execution.
 
 ### GN Configuration notes
 
 You can turn properly implemented ozone platforms on and off by setting the
 corresponding flags in your GN configuration. For example
 `ozone_platform_headless=false ozone_platform_gbm=false` will turn off the
 headless and DRM/GBM platforms.
 This will result in a smaller binary and faster builds. To turn ALL platforms
 off by default, set `ozone_auto_platforms=false`.
 
@@ skipping 58 matching lines @@
 ### Wayland
 
 This platform provides support for the
 [Wayland](http://wayland.freedesktop.org/) display protocol. It was
 initially developed by Intel as
 [a fork of chromium](https://github.com/01org/ozone-wayland)
 and then partially upstreamed.
 It is still actively being developed in the chromium tree, feel free to discuss
 with us on freenode.net, `#ozone-wayland` channel or on `ozone-dev`.
 
-In order to run an Ozone build of `chrome`, you currently (2016/10/28)
-need to compile it for ChromeOS, where software rendering is not allowed.
-Also, accelerated rendering only works in Ozone/Wayland when the UI and GPU
-components are running in the same process. Below are some quick build & run
-instructions. It is assumed that you are launching `chrome` from a Wayland
-environment such as `weston`.
+Below are some quick build & run instructions. It is assumed that you are
+launching `chrome` from a Wayland environment such as `weston`. Apply
+[this patch](https://codereview.chromium.org/2485673002/) and execute the
+following commands:
 
 ``` shell
-gn args out/OzoneWayland --args="use_ozone=true ozone_platform_wayland=true target_os=\"chromeos\""
+gn args out/OzoneWayland --args="use_ozone=true enable_package_mash_services=true"
 ninja -C out/OzoneWayland chrome
 ./out/OzoneWayland/chrome --ozone-platform=wayland \
-                          --in-process-gpu \
+                          --mash \
                           --disable-setuid-sandbox

[tonikitoo, 2016/11/08 13:09:21]

can we launch with it, if we build the 'chrome_sandbox' target?

[fwang, 2016/11/08 13:12:18]

I guess so. But I think the sandbox and all these --disable-setuid-sandbox
option changes should be handled in a separate CL.

 ```
 
 ### Caca
 
 This platform
 draws graphical output to text using
 [libcaca](http://caca.zoy.org/wiki/libcaca)
 (no GPU support; software
 rendering only). In case you ever wanted to test embedded content shell on
 tty.
@@ skipping 16 matching lines @@
 ./out/OzoneCaca/content_shell --disable-setuid-sandbox
 ```
 
   Note: traditional TTYs are not the ideal browsing experience.<br/>
   [![Picture of a workstation using Ozone/caca to display the Google home page in a text terminal](https://www.chromium.org/_/rsrc/1396307876689/developers/design-documents/ozone/IMG_20140331_151619.jpg?height=240&amp;width=320)](https://www.chromium.org/developers/design-documents/ozone/IMG_20140331_151619.jpg?attredirects=0)
 
 ## Communication
 
 There is a public mailing list:
 [ozone-dev@chromium.org](https://groups.google.com/a/chromium.org/forum/#!forum/ozone-dev)