Replace scoped_ptr with unique_ptr in webrtc/modules/desktop_capture/

BUG=webrtc:5520

Review URL: https://codereview.webrtc.org/1743203002

Cr-Commit-Position: refs/heads/master@{#12023}
diff --git a/webrtc/modules/desktop_capture/screen_capturer_helper.h b/webrtc/modules/desktop_capture/screen_capturer_helper.h
index da1f2bf..f912378 100644
--- a/webrtc/modules/desktop_capture/screen_capturer_helper.h
+++ b/webrtc/modules/desktop_capture/screen_capturer_helper.h
@@ -11,7 +11,8 @@
 #ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURER_HELPER_H_
 #define WEBRTC_MODULES_DESKTOP_CAPTURE_SCREEN_CAPTURER_HELPER_H_
 
-#include "webrtc/base/scoped_ptr.h"
+#include <memory>
+
 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
 #include "webrtc/modules/desktop_capture/desktop_region.h"
 #include "webrtc/system_wrappers/include/rw_lock_wrapper.h"
@@ -70,7 +71,7 @@
   DesktopRegion invalid_region_;
 
   // A lock protecting |invalid_region_| across threads.
-  rtc::scoped_ptr<RWLockWrapper> invalid_region_lock_;
+  std::unique_ptr<RWLockWrapper> invalid_region_lock_;
 
   // The size of the most recently captured screen.
   DesktopSize size_most_recent_;