[WebRTC] Add ScreenCapturerDifferWrapper to share Differ across ScreenCapturers

webrtc/modules/BUILD.gn

 # Copyright (c) 2016 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/webrtc.gni")
 import("audio_coding/audio_coding.gni")
@@ skipping 345 matching lines @@
         "desktop_capture/differ_block_unittest.cc",
         "desktop_capture/differ_unittest.cc",
       ]
     }
 
     if (rtc_desktop_capture_supported) {
       deps += [ "desktop_capture" ]
       sources += [
         "desktop_capture/desktop_and_cursor_composer_unittest.cc",
         "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.cc",
         "desktop_capture/screen_capturer_mock_objects.h",
         "desktop_capture/screen_capturer_unittest.cc",
         "desktop_capture/win/cursor_unittest.cc",
         "desktop_capture/win/cursor_unittest_resources.h",
         "desktop_capture/win/cursor_unittest_resources.rc",
         "desktop_capture/window_capturer_unittest.cc",
       ]
     }
 
     if (rtc_prefer_fixed_point) {
@@ skipping 233 matching lines @@
         "audio_device/ios/objc/RTCAudioSessionTest.mm",
         "video_coding/codecs/h264/h264_video_toolbox_nalu_unittest.cc",
       ]
 
       ldflags = [ "-ObjC" ]
 
       # TODO(kjellander): Mac bundle files.
     }
   }
 }