Add GN Build file for ui/events/ozone.

This was tested with:

$ gn gen out/Debug_gn --args='use_ozone=true'
$ ninja -C out/Debug_gn events_ozone events_ozone_evdev

BUG=None
TEST=see above
R=brettw@chromium.org
TBR=ben@chromium # for ui/ changes
NOTRY=true

Review URL: https://codereview.chromium.org/322983002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@276044 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

config/linux/BUILD.gn

@@ -4,6 +4,7 @@
 
 import("//build/config/linux/pkg_config.gni")
 import("//build/config/sysroot.gni")
+import("//build/config/ui.gni")
 
 config("sdk") {
   if (sysroot != "") {
@@ -52,6 +53,16 @@ pkg_config("dbus") {
   packages = [ "dbus-1" ]
 }
 
+if (use_evdev_gestures) {
+  pkg_config("libevdev-cros") {
+    packages = [ "libevdev-cros" ]
+  }
+
+  pkg_config("libgestures") {
+    packages = [ "libgestures" ]
+  }
+}
+
 config("x11") {
   # Don't bother running pkg-config for these X related libraries since it just
   # returns the same libs, and forking pkg-config is slow.

config/ui.gni

@@ -20,6 +20,9 @@ declare_args() {
   # that does not require X11.
   use_ozone = false
 
+  # Support ChromeOS touchpad gestures with ozone.
+  use_evdev_gestures = false
+
   # Indicates if Aura is enabled. Aura is a low-level windowing library, sort
   # of a replacement for GDI or GTK.
   use_aura = is_linux || use_ozone || is_win || is_chromeos || use_ash
@@ -53,6 +56,8 @@ use_default_render_theme = use_aura || is_linux
 # Indicates if the UI toolkit depends on X11.
 use_x11 = is_linux && !use_ozone
 
+use_ozone_evdev = use_ozone
+
 use_glib = is_linux
 
 use_clipboard_aurax11 = is_linux && use_aura && use_x11