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

webrtc/modules/desktop_capture/desktop_geometry.cc

Index: webrtc/modules/desktop_capture/desktop_geometry.cc
diff --git a/webrtc/modules/desktop_capture/desktop_geometry.cc b/webrtc/modules/desktop_capture/desktop_geometry.cc
index 2af8cf826e4dc70193e58569b0e6824eddc140de..37b31998272afdb01f66402b8a6dca3e74bd8544 100644
--- a/webrtc/modules/desktop_capture/desktop_geometry.cc
+++ b/webrtc/modules/desktop_capture/desktop_geometry.cc
@@ -37,6 +37,20 @@ void DesktopRect::IntersectWith(const DesktopRect& rect) {
   }
 }
 
+void DesktopRect::UnionWith(const DesktopRect& rect) {
+  if (is_empty()) {
+    left_ = rect.left();

[Sergey Ulanov, 2017/05/16 19:53:00]

*this = rect;

[Hzj_jie, 2017/05/16 23:04:18]

Done.

+    top_ = rect.top();
+    right_ = rect.right();
+    bottom_ = rect.bottom();
+  } else if (!rect.is_empty()) {

[Sergey Ulanov, 2017/05/16 19:53:00]

I'd prefer to format this function as follows:

  if (is_empty()) {
    *this = rect;
    return;
  }

  if (rect.is_empty())
    return;  

  left_ = std::min(left(), rect.left());
  top_ = std::min(top(), rect.top());
  right_ = std::max(right(), rect.right());
  bottom_ = std::max(bottom(), rect.bottom());

This makes the default case obvious and separates it from the cases when one of
the rects is empty

[Hzj_jie, 2017/05/16 23:04:18]

Done.

+    left_ = std::min(left(), rect.left());
+    top_ = std::min(top(), rect.top());
+    right_ = std::max(right(), rect.right());
+    bottom_ = std::max(bottom(), rect.bottom());
+  }
+}
+
 void DesktopRect::Translate(int32_t dx, int32_t dy) {
   left_ += dx;
   top_ += dy;