Deflaky ScreenCapturerTest

webrtc/modules/desktop_capture/screen_drawer.h

 /*
  *  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.
  */
 
 #ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_SCREEN_DRAWER_H_
 #define WEBRTC_MODULES_DESKTOP_CAPTURE_SCREEN_DRAWER_H_
 
 #include <stdint.h>
 
 #include <memory>
 
 #include "webrtc/modules/desktop_capture/rgba_color.h"
 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
 
 namespace webrtc {
 
 // A set of basic platform dependent functions to draw various shapes on the
 // screen.
 class ScreenDrawer {
  public:
   // Creates a ScreenDrawer for the current platform, returns nullptr if no
   // ScreenDrawer implementation available.
+  // If the implementation cannot guarantee two ScreenDrawer instances won't
+  // impact each other, this function may block current thread until another
+  // ScreenDrawer has been destroyed.
   static std::unique_ptr<ScreenDrawer> Create();
 
   ScreenDrawer() {}
   virtual ~ScreenDrawer() {}
 
   // Returns the region inside which DrawRectangle() function are expected to
   // work, in capturer coordinates (assuming ScreenCapturer::SelectScreen has
   // not been called). This region may exclude regions of the screen reserved by
   // the OS for things like menu bars or app launchers.
   virtual DesktopRect DrawableRegion() = 0;
 
   // Draws a rectangle to cover |rect| with |color|. Note, rect.bottom() and
   // rect.right() two lines are not included. The part of |rect| which is out of
   // DrawableRegion() will be ignored.
   virtual void DrawRectangle(DesktopRect rect, RgbaColor color) = 0;
 
   // Clears all content on the screen by filling the area with black.
   virtual void Clear() = 0;
 
   // Blocks current thread until OS finishes previous DrawRectangle() actions.
   // ScreenCapturer should be able to capture the changes after this function
   // finish.
   virtual void WaitForPendingDraws() = 0;
+
+  // Returns true if incomplete shapes previous actions required may be drawn on
+  // the screen after a WaitForPendingDraws() call. i.e. Though the complete
+  // shapes will eventually be drawn on the screen, due to some OS limitations,
+  // these shapes may be partially appeared sometimes.
+  virtual bool MayDrawIncompleteShapes() = 0;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_SCREEN_DRAWER_H_