Add CreateWindowCapturer() and CreateScreenCapturer() in DesktopCapturer

webrtc/modules/desktop_capture/desktop_capturer.cc

Index: webrtc/modules/desktop_capture/desktop_capturer.cc
diff --git a/webrtc/modules/desktop_capture/desktop_capturer.cc b/webrtc/modules/desktop_capture/desktop_capturer.cc
index a18976a62664a476534de69b2d29e567f7661bd6..f28630e9c450a1ca2aaa0d3bd9ad86da5942b982 100644
--- a/webrtc/modules/desktop_capture/desktop_capturer.cc
+++ b/webrtc/modules/desktop_capture/desktop_capturer.cc
@@ -11,7 +11,7 @@
 #include "webrtc/modules/desktop_capture/desktop_capturer.h"
 
 #include "webrtc/modules/desktop_capture/desktop_capture_options.h"
-#include "webrtc/modules/desktop_capture/screen_capturer_differ_wrapper.h"
+#include "webrtc/modules/desktop_capture/desktop_capturer_differ_wrapper.h"
 
 namespace webrtc {
 
@@ -34,4 +34,32 @@ bool DesktopCapturer::FocusOnSelectedSource() {
   return false;
 }
 
+// Some platforms, such as ChromeOS, have their DesktopCapturer implementations
+// in Chromium. So even we do not have CreateRawWindowCapturer() or
+// CreateRawScreenCapturer() implemented in WebRTC, we still need to build other
+// DesktopCapturer components when RTC_DESKTOP_CAPTURE_SUPPORTED is not defined.
+#if defined(RTC_DESKTOP_CAPTURE_SUPPORTED)
+// static
+std::unique_ptr<DesktopCapturer> DesktopCapturer::CreateWindowCapturer(
+    const DesktopCaptureOptions& options) {
+  std::unique_ptr<DesktopCapturer> capturer = CreateRawWindowCapturer(options);
+  if (options.detect_updated_region()) {
+    capturer.reset(new DesktopCapturerDifferWrapper(std::move(capturer)));
+  }
+
+  return capturer;
+}
+
+// static
+std::unique_ptr<DesktopCapturer> DesktopCapturer::CreateScreenCapturer(
+    const DesktopCaptureOptions& options) {
+  std::unique_ptr<DesktopCapturer> capturer = CreateRawScreenCapturer(options);
+  if (options.detect_updated_region()) {
+    capturer.reset(new DesktopCapturerDifferWrapper(std::move(capturer)));
+  }
+
+  return capturer;
+}
+#endif  // defined(RTC_DESKTOP_CAPTURE_SUPPORTED)
+
 }  // namespace webrtc