Add CreateWindowCapturer() and CreateScreenCapturer() in DesktopCapturer

webrtc/modules/desktop_capture/desktop_capturer.cc

 /*
  *  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.
  */
 
 #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 {
 
 DesktopCapturer::~DesktopCapturer() = default;
 
 void DesktopCapturer::SetSharedMemoryFactory(
     std::unique_ptr<SharedMemoryFactory> shared_memory_factory) {}
 
 void DesktopCapturer::SetExcludedWindow(WindowId window) {}
 
 bool DesktopCapturer::GetSourceList(SourceList* sources) {
   return true;
 }
 
 bool DesktopCapturer::SelectSource(SourceId id) {
   return false;
 }
 
 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