wm: Do not resize when switching users if window is already maximized.

chrome/browser/ui/ash/multi_user/user_switch_animator_chromeos.cc

Index: chrome/browser/ui/ash/multi_user/user_switch_animator_chromeos.cc
diff --git a/chrome/browser/ui/ash/multi_user/user_switch_animator_chromeos.cc b/chrome/browser/ui/ash/multi_user/user_switch_animator_chromeos.cc
index c4935d7a3b700b6449410863c525d300836f1b69..7f1f8b789205ea8d01128c1bde7d330179e375cc 100644
--- a/chrome/browser/ui/ash/multi_user/user_switch_animator_chromeos.cc
+++ b/chrome/browser/ui/ash/multi_user/user_switch_animator_chromeos.cc
@@ -145,8 +145,10 @@ bool UserSwitchAnimatorChromeOS::CoversScreen(aura::Window* window) {
   gfx::Rect bounds = window->GetBoundsInRootWindow();
   gfx::Rect work_area =
       display::Screen::GetScreen()->GetDisplayNearestWindow(window).work_area();
-  bounds.Intersect(work_area);
-  return work_area == bounds;
+  // |work_area| may be on a different display, so we cannot just check the
+  // intersection of |work_area| and |bounds|, so just check if their sizes are
+  // equal to see if |bounds| covers |work_area|.
+  return work_area.size() == bounds.size();

[Mr4D (OOO till 08-26), 2017/06/09 23:50:25]

If you have a window which has the same size as maximized - but it is not, the
user can move it off the origin of the screen (which might not even be (0,0) but
(shelfwidth, 0) ) and then this would be reported as covers screen - which it is
not.

[sammiequon, 2017/06/10 00:04:49]

I see, I *think* GetBoundsInScreen() would do.

 }
 
 void UserSwitchAnimatorChromeOS::AdvanceUserTransitionAnimation() {