GN: Tighten up test target visibility + refactorings

webrtc/modules/desktop_capture/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/config/ui.gni")
 import("../../webrtc.gni")
@@ skipping 17 matching lines @@
 
   deps = [
     "../..:webrtc_common",
     "../../base:rtc_base",  # TODO(kjellander): Cleanup in bugs.webrtc.org/3806.
   ]
 }
 
 if (rtc_include_tests) {
   rtc_source_set("desktop_capture_modules_tests") {
     testonly = true
+    if (!is_android && !is_ios) {  # Generated targets makes this check break.
+      visibility = [ "//webrtc/modules:modules_tests" ]
+    }
     sources = []
     deps = []
     if (rtc_desktop_capture_supported) {
       deps += [
         ":desktop_capture_mock",
         ":primitives",
         ":screen_drawer",
         "../../base:rtc_base",
         "../../base:rtc_base_approved",
         "../../system_wrappers",
         "../../test:test_support",
         "../../test:video_test_support",
       ]
       sources += [
         "screen_capturer_integration_test.cc",
         "screen_drawer_unittest.cc",
       ]
     }
   }
 
   rtc_source_set("desktop_capture_unittests") {
     testonly = true
+    if (!is_android && !is_ios) {  # Generated targets makes this check break.
+      visibility = [ "//webrtc/modules:modules_unittests" ]
+    }
     sources = [
       "blank_detector_desktop_capturer_wrapper_unittest.cc",
       "desktop_and_cursor_composer_unittest.cc",
       "desktop_capturer_differ_wrapper_unittest.cc",
       "desktop_frame_rotation_unittest.cc",
       "desktop_region_unittest.cc",
       "differ_block_unittest.cc",
       "fallback_desktop_capturer_wrapper_unittest.cc",
       "mouse_cursor_monitor_unittest.cc",
       "rgba_color_unittest.cc",
@@ skipping 219 matching lines @@
     sources = [
       "differ_vector_sse2.cc",
       "differ_vector_sse2.h",
     ]
 
     if (is_posix) {
       cflags = [ "-msse2" ]
     }
   }
 }