Wrap ScreenCapturer with ScreenCapturerDifferWrapper

webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc

Index: webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc
diff --git a/webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc b/webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc
index e4b2c3e8a225b397d4c67693baa646c2c98c34f3..4201fcee3a18abd684e20da7779eec2067c6c416 100644
--- a/webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc
+++ b/webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc
@@ -16,16 +16,31 @@
 #include "webrtc/base/logging.h"
 #include "webrtc/base/timeutils.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
+#include "webrtc/modules/desktop_capture/screen_capturer_differ_wrapper.h"
 
 namespace webrtc {
 
 using Microsoft::WRL::ComPtr;
 
+// static
 bool ScreenCapturerWinDirectx::IsSupported() {
   // Forward IsSupported function call to DxgiDuplicatorController.
   return DxgiDuplicatorController::Instance()->IsSupported();
 }
 
+// static
+std::unique_ptr<ScreenCapturer> ScreenCapturerWinDirectx::Create(
+    const DesktopCaptureOptions& options) {
+  if (!IsSupported()) {
+    return std::unique_ptr<ScreenCapturer>();

[Sergey Ulanov, 2016/09/07 22:47:23]

return nullptr;

+  }
+
+  // Windows is known to return larger updated region, so we wrap a
+  // ScreenCapturerDirectx instance with ScreenCapturerDifferWrapper.
+  return std::unique_ptr<ScreenCapturer>(new ScreenCapturerDifferWrapper(

[Sergey Ulanov, 2016/09/07 22:47:23]

I think it's better to keep this code in ScreenCapturer::Create(). It doesn't
look right that ScreenCapturerWinDirectx::Create() creates a capturer that isn't
ScreenCapturerWinDirectx

+      std::unique_ptr<ScreenCapturer>(new ScreenCapturerWinDirectx(options))));
+}
+
 ScreenCapturerWinDirectx::ScreenCapturerWinDirectx(
     const DesktopCaptureOptions& options)
     : callback_(nullptr) {}