Fix wayland-chrome build.

atomic cannot be used on chromeos platform.

BUG=1043804
TEST=Build locally.

Change-Id: I0c9ab4682f2bdf25cf966d4a581ee666a588bd16
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2057504
Commit-Queue: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742043}

build/config/linux/BUILD.gn

@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("//build/config/c++/c++.gni")
+import("//build/config/chromeos/ui_mode.gni")
 import("//build/config/linux/pkg_config.gni")
 import("//build/config/ui.gni")
 
@@ -27,7 +28,8 @@ config("runtime_library") {
     defines = [ "OS_CHROMEOS" ]
   }
 
-  if ((!is_chromeos || default_toolchain != "//build/toolchain/cros:target") &&
+  if ((!(is_chromeos || chromeos_is_browser_only) ||
+       default_toolchain != "//build/toolchain/cros:target") &&
       (!use_custom_libcxx || current_cpu == "mipsel")) {
     libs = [ "atomic" ]
   }