Expand is_linux to is_linux || is_chromeos.

Currently is_linux is set to true on Chrome OS build,
but it is planned to be set false. This CL is the preparation
to keep the compatibility.

Bug: chromium:1110266
Test: Build locally.
Change-Id: Ic79a202b0b3baeff157955cd03a07556bfb958a8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/183860
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Hidehiko Abe <hidehiko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#32073}
diff --git a/webrtc.gni b/webrtc.gni
index 17a66f9..420fb7f 100644
--- a/webrtc.gni
+++ b/webrtc.gni
@@ -279,7 +279,7 @@
 # Desktop capturer is supported only on Windows, OSX and Linux.
 rtc_desktop_capture_supported =
     (is_win && current_os != "winuwp") || is_mac ||
-    (is_linux && (rtc_use_x11_extensions || rtc_use_pipewire))
+    ((is_linux || is_chromeos) && (rtc_use_x11_extensions || rtc_use_pipewire))
 
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