Wrap ScreenCapturer with ScreenCapturerDifferWrapper

webrtc/modules/desktop_capture/screen_capturer_win.cc

Index: webrtc/modules/desktop_capture/screen_capturer_win.cc
diff --git a/webrtc/modules/desktop_capture/screen_capturer_win.cc b/webrtc/modules/desktop_capture/screen_capturer_win.cc
index 6a83bec1c522218e039063fa8f3177f6ade71562..5b36a7a527b4a2ea41db346047de15f943c806b1 100644
--- a/webrtc/modules/desktop_capture/screen_capturer_win.cc
+++ b/webrtc/modules/desktop_capture/screen_capturer_win.cc
@@ -14,6 +14,7 @@
 #include <utility>
 
 #include "webrtc/modules/desktop_capture/desktop_capture_options.h"
+#include "webrtc/modules/desktop_capture/screen_capturer_differ_wrapper.h"
 #include "webrtc/modules/desktop_capture/win/screen_capturer_win_directx.h"
 #include "webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.h"
 #include "webrtc/modules/desktop_capture/win/screen_capturer_win_magnifier.h"
@@ -23,15 +24,19 @@ namespace webrtc {
 // static
 ScreenCapturer* ScreenCapturer::Create(const DesktopCaptureOptions& options) {
   std::unique_ptr<ScreenCapturer> capturer;
-  if (options.allow_directx_capturer() &&
-      ScreenCapturerWinDirectx::IsSupported()) {
+  if (options.allow_directx_capturer()) {

[Sergey Ulanov, 2016/09/09 17:33:51]

Do you still need to check IsSupported() here?

[Hzj_jie, 2016/09/14 19:35:31]

Oh, yes, I still need to check IsSupport here.

This should be able to be caught by the test case. I will also update the
screen_capturer_unittest.cc

     capturer.reset(new ScreenCapturerWinDirectx(options));
-  } else {
+  }
+  if (!capturer) {

[Sergey Ulanov, 2016/09/09 17:33:51]

else is still appropriate here.

[Hzj_jie, 2016/09/14 19:35:31]

Done.

     capturer.reset(new ScreenCapturerWinGdi(options));
   }
+  if (options.allow_use_magnification_api()) {
+    capturer.reset(new ScreenCapturerWinMagnifier(std::move(capturer)));
+  }
 
-  if (options.allow_use_magnification_api())
-    return new ScreenCapturerWinMagnifier(std::move(capturer));
+  if (options.detect_updated_region()) {
+    capturer.reset(new ScreenCapturerDifferWrapper(std::move(capturer)));
+  }
 
   return capturer.release();
 }