Adding missing wgl_api_unittest.cc to Windows gn build

ui/gl/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 
 use_egl = is_win || is_android || is_linux
 use_glx = use_x11
 
@@ skipping 345 matching lines @@
 
   if (use_ozone) {
     sources += [ "gl_image_ozone_native_pixmap_unittest.cc" ]
   }
 
   if (is_mac) {
     sources += [ "gl_image_io_surface_unittest.cc" ]
     libs = [ "IOSurface.framework" ]
   }
 
+  if (is_win) {
+    sources += [ "wgl_api_unittest.cc" ]
+  }
+
   include_dirs = [ "//third_party/khronos" ]
 
   deps = [
     ":gl",
     ":gl_unittest_utils",
     ":test_support",
     "//base",
     "//base/test:test_support",
     "//testing/gmock",
     "//testing/gtest",
@@ skipping 21 matching lines @@
     sources = [
       "../android/java/src/org/chromium/ui/gl/SurfaceTextureListener.java",
       "../android/java/src/org/chromium/ui/gl/SurfaceTexturePlatformWrapper.java",
     ]
     public_deps = [
       ":surface_jni_headers",
     ]
     jni_package = "ui/gl"
   }
 }