[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 92284a1da6c4e77f6b949c7d7cd643dda335a52d..6a4701b7fff0cf4550cc2f2c721244d8792c79e2 100644
--- a/webrtc/modules/BUILD.gn
+++ b/webrtc/modules/BUILD.gn
@@ -505,7 +505,13 @@ 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",