Add initial SHM-only Wayland Ozone implementation

ui/ozone/ozone.gni

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/chromecast_build.gni")
 import("//build/config/ui.gni")
 
 declare_args() {
   # Select platforms automatically. Turn this off for manual control.
   ozone_auto_platforms = use_ozone
@@ skipping 11 matching lines @@
   ozone_platform = ""
 
   # Enable individual platforms.
   ozone_platform_caca = false
   ozone_platform_cast = false
   ozone_platform_egltest = false
   ozone_platform_gbm = false
   ozone_platform_ozonex = false
   ozone_platform_headless = false
   ozone_platform_x11 = false
+  ozone_platform_wayland = false
 
   if (ozone_auto_platforms) {
     # Use headless as the default platform.
     ozone_platform = "headless"
     ozone_platform_headless = true
 
     if (is_chromecast) {
       if (!disable_display) {
         # Enable the Cast ozone platform on all A/V Cast builds.
         ozone_platform_cast = true
@@ skipping 19 matching lines @@
       # Only these platforms will be compile tested by buildbots.
       ozone_platform_egltest = true
     }
   }
 }
 
 assert(use_ozone || !(ozone_platform_caca || ozone_platform_cast ||
                           ozone_platform_egltest || ozone_platform_gbm ||
                           ozone_platform_ozonex || ozone_platform_headless),
        "Must set use_ozone to select ozone platforms")