GN: Refactor modules_unittests to eliminate package boundary violations.

webrtc/modules/desktop_capture/BUILD.gn

Index: webrtc/modules/desktop_capture/BUILD.gn
diff --git a/webrtc/modules/desktop_capture/BUILD.gn b/webrtc/modules/desktop_capture/BUILD.gn
index 67ec8cea3751b7742fcbaa71d282041c51c109eb..b234232c6798e91010490ac92dfe8b56d8c68320 100644
--- a/webrtc/modules/desktop_capture/BUILD.gn
+++ b/webrtc/modules/desktop_capture/BUILD.gn
@@ -33,6 +33,27 @@ rtc_static_library("primitives") {
 }
 
 if (rtc_include_tests) {
+  rtc_source_set("desktop_capture_modules_tests") {
+    testonly = true
+    sources = []
+    deps = []
+    if (rtc_desktop_capture_supported) {
+      deps += [
+        ":desktop_capture_mock",
+        ":primitives",
+        ":screen_drawer",
+        "../../base:rtc_base",
+        "../../base:rtc_base_approved",
+        "../../system_wrappers:system_wrappers",
+        "../../test:test_support",
+      ]
+      sources += [
+        "screen_capturer_integration_test.cc",
+        "screen_drawer_unittest.cc",
+      ]
+    }
+  }
+
   rtc_source_set("desktop_capture_unittests") {
     testonly = true
     sources = []