Condition the use of ChromeBrowserMainExtraPartsViewsLinux to !use_ozone

chrome/browser/ui/BUILD.gn

Index: chrome/browser/ui/BUILD.gn
diff --git a/chrome/browser/ui/BUILD.gn b/chrome/browser/ui/BUILD.gn
index 92278a95ea20df935ecc69ec9413f49e3751ace2..a0405717449e9013a4619671d45060a0e0b8b940 100644
--- a/chrome/browser/ui/BUILD.gn
+++ b/chrome/browser/ui/BUILD.gn
@@ -1520,8 +1520,6 @@ split_static_library("ui") {
       sources += [
         "external_protocol_dialog_delegate.cc",
         "external_protocol_dialog_delegate.h",
-        "views/chrome_browser_main_extra_parts_views_linux.cc",
-        "views/chrome_browser_main_extra_parts_views_linux.h",
         "views/external_protocol_dialog.cc",
         "views/external_protocol_dialog.h",
         "views/frame/opaque_browser_frame_view.cc",
@@ -1542,6 +1540,18 @@ split_static_library("ui") {
         "views/sync/profile_signin_confirmation_dialog_views.h",
       ]
     }
+
+    # These files do Gtk+-based theming, but Gtk+ is not available on
+    # Ozone builds, or on common environments where Ozone will be used.
+    #
+    # TODO(tonikitoo): It seems sensible to make it possible to opt-in
+    # the use of these files in case Gtk is available with its Wayland.
+    if (use_aura && !use_ozone && is_desktop_linux) {
+      sources += [
+        "views/chrome_browser_main_extra_parts_views_linux.cc",
+        "views/chrome_browser_main_extra_parts_views_linux.h",
+      ]
+    }
     if (enable_extensions && (!is_mac || mac_views_browser)) {
       sources += [
         "views/extensions/bookmark_app_confirmation_view.cc",