Realign message center popups when displays are added or removed

ui/message_center/views/desktop_popup_alignment_delegate.cc

Index: ui/message_center/views/desktop_popup_alignment_delegate.cc
diff --git a/ui/message_center/views/desktop_popup_alignment_delegate.cc b/ui/message_center/views/desktop_popup_alignment_delegate.cc
index f67200def64ace65e3e331bb51c73008d401fac8..9ed93d35e1c94db35a7dac8422989e847e543314 100644
--- a/ui/message_center/views/desktop_popup_alignment_delegate.cc
+++ b/ui/message_center/views/desktop_popup_alignment_delegate.cc
@@ -84,10 +84,24 @@ void DesktopPopupAlignmentDelegate::RecomputeAlignment(
 }
 
 void DesktopPopupAlignmentDelegate::OnDisplayAdded(
-    const display::Display& new_display) {}
+    const display::Display& new_display) {

[dewittj, 2016/06/20 17:06:00]

rename to added_display

[Jun Mukai, 2016/06/20 20:28:54]

Can you also leave a comment for why these are necessary?

That would be something like:

// Primary display can change upon adding or removing display, and
// this will have to recompute the alignment on the new screen.

[osandov, 2016/06/21 08:01:05]

Done.

[osandov, 2016/06/21 08:01:06]

Done.

+  display::Display display = screen_->GetPrimaryDisplay();

[dewittj, 2016/06/20 17:06:00]

nit: rename to primary_display

[osandov, 2016/06/21 08:01:05]

This moved after refactoring, but also done.

+  if (new_display.id() == display.id() && display.id() != display_id_) {
+    display_id_ = display.id();
+    RecomputeAlignment(display);

[dewittj, 2016/06/20 17:06:00]

Lots of code duplication between these, could you please refactor into a helper
function?

[osandov, 2016/06/21 08:01:06]

Done.

+    DoUpdateIfPossible();
+  }
+}
 
 void DesktopPopupAlignmentDelegate::OnDisplayRemoved(
-    const display::Display& old_display) {}
+    const display::Display& old_display) {

[dewittj, 2016/06/20 17:06:00]

rename to removed_display

[osandov, 2016/06/21 08:01:06]

Done.

+  if (old_display.id() == display_id_) {
+    display::Display display = screen_->GetPrimaryDisplay();

[dewittj, 2016/06/20 17:05:59]

primary_display

[osandov, 2016/06/21 08:01:06]

Done, moved in the refactoring.

+    display_id_ = display.id();
+    RecomputeAlignment(display);
+    DoUpdateIfPossible();
+  }
+}
 
 void DesktopPopupAlignmentDelegate::OnDisplayMetricsChanged(
     const display::Display& display,