Split //ui/events/devices into two targets.

ui/base/BUILD.gn

Index: ui/base/BUILD.gn
diff --git a/ui/base/BUILD.gn b/ui/base/BUILD.gn
index 6390bd4e1e8b2ea2137cbb1e1b28e9965e7503ce..a4f296f2ccc4df0b0b643359dd680fd8c8da1234 100644
--- a/ui/base/BUILD.gn
+++ b/ui/base/BUILD.gn
@@ -412,6 +412,8 @@ component("base") {
       "dragdrop/drag_utils_aura.cc",
     ]
   }
+
+  # TODO(kylechar): remove ozone_platform_x11 from here.
   if (use_x11 || ozone_platform_x11) {
     sources += [
       "x/x11_foreign_window_manager.cc",
@@ -431,7 +433,10 @@ component("base") {
       ]
       configs += [ "//build/config/linux:xscrnsaver" ]
     }
-    deps += [ "//ui/gfx/x" ]
+    deps += [
+      "//ui/events/devices/x11",
+      "//ui/gfx/x",
+    ]
   }
 
   if (!use_aura || !is_linux) {