Add ui/gfx/x/x11.h to //ui/gfx/x sources

This include file was missing from any BUILD.gn file. This CL also fixes
the missing dependency on //ui/gfx/x from targets that include that file
and also marks some of those includes as nogncheck in cases where the
target is compiled with !use_x11 (e.g. Chrome OS).

Change-Id: Ia5efd1797df721f2bfc9138093270a66402cf2d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2108540
Reviewed-by: Thomas Anderson <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Commit-Queue: Henrique Ferreiro <[email protected]>
Cr-Commit-Position: refs/heads/master@{#763248}
diff --git a/content/browser/BUILD.gn b/content/browser/BUILD.gn
index 4befa92..f9d1a4ff 100644
--- a/content/browser/BUILD.gn
+++ b/content/browser/BUILD.gn
@@ -2324,6 +2324,8 @@
       "//build/config/linux/atspi2",
     ]
 
+    deps += [ "//ui/gfx/x" ]
+
     if (use_glib) {
       configs += [ "//build/config/linux:glib" ]
     }