Ozone: Remove the use_wayland_egl build flag

ui/ozone/platform/wayland/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 visibility = [ "//ui/ozone/*" ]
 
 import("//build/config/linux/pkg_config.gni")
 
-declare_args() {
-  use_wayland_egl = true
-}
-
-if (use_wayland_egl) {
-  pkg_config("wayland-egl") {
-    packages = [ "wayland-egl" ]
-  }
+pkg_config("wayland-egl") {
+  packages = [ "wayland-egl" ]
 }
 
 source_set("wayland") {
   sources = [
     "client_native_pixmap_factory_wayland.cc",
     "client_native_pixmap_factory_wayland.h",
+    "gl_surface_wayland.cc",
+    "gl_surface_wayland.h",
     "ozone_platform_wayland.cc",
     "ozone_platform_wayland.h",
     "wayland_connection.cc",
     "wayland_connection.h",
     "wayland_object.cc",
     "wayland_object.h",
     "wayland_output.cc",
     "wayland_output.h",
     "wayland_pointer.cc",
     "wayland_pointer.h",
@@ skipping 12 matching lines @@
     "//ui/events/platform",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/ozone:ozone_base",
     "//ui/ozone/common",
     "//ui/platform_window",
   ]
 
   defines = [ "OZONE_IMPLEMENTATION" ]
 
-  if (use_wayland_egl) {
-    sources += [
-      "gl_surface_wayland.cc",
-      "gl_surface_wayland.h",
-    ]
-    configs += [
-      ":wayland-egl",
-      "//third_party/khronos:khronos_headers",
-    ]
-    defines += [ "USE_WAYLAND_EGL" ]
-  }
+  configs += [
+    ":wayland-egl",
+    "//third_party/khronos:khronos_headers",
+  ]
 }
 
 source_set("wayland_unittests") {
   testonly = true
 
   sources = [
     "fake_server.cc",
     "fake_server.h",
     "mock_platform_window_delegate.cc",
     "wayland_connection_unittest.cc",
     "wayland_pointer_unittest.cc",
     "wayland_surface_factory_unittest.cc",
     "wayland_test.cc",
     "wayland_test.h",
     "wayland_window_unittest.cc",
   ]
 
   deps = [
     ":wayland",
     "//testing/gmock",
     "//testing/gtest",
     "//third_party/wayland:wayland_server",
     "//third_party/wayland-protocols:xdg_shell_protocol",
     "//ui/gfx:test_support",
     "//ui/ozone:platform",
   ]
 
   defines = [ "WL_HIDE_DEPRECATED" ]
 }