[WebRTC] Add ScreenCapturerDifferWrapper to share Differ across ScreenCapturers

webrtc/modules/BUILD.gn

Index: webrtc/modules/BUILD.gn
diff --git a/webrtc/modules/BUILD.gn b/webrtc/modules/BUILD.gn
index e3e92a141741b15b7113c236e065bd3308ba6309..c8c9e5afe5bae1eea9ad4728cb7a57a42e6a8d33 100644
--- a/webrtc/modules/BUILD.gn
+++ b/webrtc/modules/BUILD.gn
@@ -362,7 +362,13 @@ if (rtc_include_tests) {
       deps += [ "desktop_capture" ]
       sources += [
         "desktop_capture/desktop_and_cursor_composer_unittest.cc",
+        "desktop_capture/desktop_frame_generator.cc",
+        "desktop_capture/desktop_frame_generator.h",
+        "desktop_capture/fake_desktop_capturer.h",
+        "desktop_capture/fake_screen_capturer.cc",
+        "desktop_capture/fake_screen_capturer.h",
         "desktop_capture/mouse_cursor_monitor_unittest.cc",
+        "desktop_capture/screen_capturer_differ_wrapper_unittest.cc",
         "desktop_capture/screen_capturer_helper_unittest.cc",
         "desktop_capture/screen_capturer_mac_unittest.cc",
         "desktop_capture/screen_capturer_mock_objects.h",