DesktopRect::UnionWith() to extend current rect to cover the input rect

webrtc/modules/desktop_capture/desktop_geometry.cc

 /*
  *  Copyright (c) 2013 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.
  */
 
@@ skipping 36 matching lines @@
 void DesktopRect::Extend(int32_t left_offset,
                          int32_t top_offset,
                          int32_t right_offset,
                          int32_t bottom_offset) {
   left_ -= left_offset;
   top_ -= top_offset;
   right_ += right_offset;
   bottom_ += bottom_offset;
 }
 
+void DesktopRect::UnionWith(const DesktopRect& rect) {
+  if (is_empty()) {
+    left_ = rect.left();
+    top_ = rect.top();
+    right_ = rect.right();
+    bottom_ = rect.bottom();
+  } else {
+    left_ = std::min(left(), rect.left());
+    top_ = std::min(top(), rect.top());
+    right_ = std::max(right(), rect.right());
+    bottom_ = std::max(bottom(), rect.bottom());
+  }
+}
+
 }  // namespace webrtc