Revert of BlankDetectorDesktopCapturerWrapper to detect a blank DesktopFrame

webrtc/modules/desktop_capture/rgba_color.h

Index: webrtc/modules/desktop_capture/rgba_color.h
diff --git a/webrtc/modules/desktop_capture/rgba_color.h b/webrtc/modules/desktop_capture/rgba_color.h
index 11e8d44f5f4cd70ab1944c9e26889ac0ff25cf4e..1236d03ee67c21c0c13d4c3802a5936ed97ae13a 100644
--- a/webrtc/modules/desktop_capture/rgba_color.h
+++ b/webrtc/modules/desktop_capture/rgba_color.h
@@ -21,6 +21,9 @@
 // provides functions to be created from uint8_t array, say,
 // DesktopFrame::data(). It always uses BGRA order for internal storage to match
 // DesktopFrame::data().
+//
+// This struct is for testing purpose only, and should not be used in production
+// logic.
 struct RgbaColor final {
   // Creates a color with BGRA channels.
   RgbaColor(uint8_t blue, uint8_t green, uint8_t red, uint8_t alpha);