X11 and Ozone: disable X11 specific tests in views_unittests

Enabling use_x11 && use_ozone results in running X11-only tests
that cannot succeed for Wayland config. Thus, disable them
(as it was before we started to work on use_x11 && use_ozone
config) via checking for the feature flag instead of relaying
on GN. I acknowledge that this is wrong to do, but I'm going to
fix that as soon as use_x11 && use_ozone config is upstreamed.

-----

PS: Please note that this is a temp solution that will help to choose
between ozone and non-ozone X11 build. The switch that will be used
to choose the path is --enable-features=UseOzonePlatform. Once
non-Ozone X11 path is removed (hopefully by Q1 2021 depending on how
the finch trial goes), the wrapper will be removed.

Please also note that it's impossible to build use_x11 && use_ozone
without some hacks in PlatformCursor code. The changes to that are
on their way to upstream.

----

Bug: 1085700
Change-Id: I77b943fe8e54982b97c40a4f34bbbca66ab3f726
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2336597Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Maksim Sisov (GMT+3) <msisov@igalia.com>
Cr-Commit-Position: refs/heads/master@{#794876}

ui/views/widget/desktop_aura/desktop_screen_x11_unittest.cc

@@ -16,6 +16,7 @@
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/base/hit_test.h"
+#include "ui/base/ui_base_features.h"
 #include "ui/base/x/x11_display_manager.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/display/display.h"
@@ -70,6 +71,9 @@ class DesktopScreenX11Test : public views::ViewsTestBase,
   // Overridden from testing::Test:
   void SetUp() override {
     ViewsTestBase::SetUp();
+    // TODO(msisov): rewrite desktop screen tests for ozone and non-ozone Linux.
+    if (features::IsUsingOzonePlatform())
+      GTEST_SKIP();
     // Initialize the world to the single monitor case.
     std::vector<display::Display> displays;
     displays.emplace_back(kFirstDisplay, gfx::Rect(0, 0, 640, 480));

ui/views/widget/desktop_aura/x11_drag_drop_client_unittest.cc

@@ -487,6 +487,9 @@ class X11DragDropClientTest : public ViewsTestBase {
     set_native_widget_type(NativeWidgetType::kDesktop);
 
     ViewsTestBase::SetUp();
+    // TODO(msisov): rewrite these tests for ozone and non-ozone Linux.
+    if (features::IsUsingOzonePlatform())
+      GTEST_SKIP();
 
     // Create widget to initiate the drags.
     widget_ = std::make_unique<Widget>();