Fix wrong layout in login shelf view

ShelfWidget's bounds are offset to leave space for the navigation
widget even when the login shelf shows. It leads to the wrong layout
of the login shelf. This CL fixes such an issue.


Bug: 994424
Change-Id: I2f422e2a53e7d40f76ebbbb53204e1619ccc95e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1811642Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Andrew Xu <andrewxu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697815}

ash/shelf/shelf_layout_manager.cc

@@ -1419,7 +1419,8 @@ void ShelfLayoutManager::CalculateTargetBounds(
 
   // This needs to happen after calling UpdateTargetBoundsForGesture(), because
   // that can change the size of the shelf.
-  if (chromeos::switches::ShouldShowScrollableShelf()) {
+  const bool showing_login_shelf = !state.IsActiveSessionState();
+  if (chromeos::switches::ShouldShowScrollableShelf() && !showing_login_shelf) {
     target_bounds->shelf_bounds_in_shelf = SelectValueForShelfAlignment(
         gfx::Rect(target_bounds->nav_bounds_in_shelf.right(), 0,
                   shelf_width - status_size.width() -