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

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/ash/multi_user/user_switch_animator_chromeos.h"
 
 #include "ash/root_window_controller.h"
 #include "ash/shelf/shelf.h"
 #include "ash/shelf/shelf_layout_manager.h"
 #include "ash/shelf/shelf_widget.h"
@@ skipping 127 matching lines @@
 // static
 bool UserSwitchAnimatorChromeOS::CoversScreen(aura::Window* window) {
   // Full screen covers the screen naturally. Since a normal window can have the
   // same size as the work area, we only compare the bounds against the work
   // area.
   if (ash::wm::GetWindowState(window)->IsFullscreen())
     return true;
   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() {
   DCHECK_NE(animation_step_, ANIMATION_STEP_ENDED);
 
   TransitionWallpaper(animation_step_);
   TransitionUserShelf(animation_step_);
   TransitionWindows(animation_step_);
 
   // Advance to the next step.
@@ skipping 273 matching lines @@
         if (itr != window_to_entry_map.end()) {
           windows_by_account_id_[itr->second->show_for_user()].push_back(
               child_window);
         }
       }
     }
   }
 }
 
 }  // namespace chrome