[Tab Group Collapse] Keyboard does not move tabs into a collapsed group.

Using F6 to cycle to a tab, then using CTRL+LEFT/RIGHT will not move a
tab into a collapsed group.

Bug: 1018230
Change-Id: I497075710186a8ab0d67971aa9fc203147057dc4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2219402Reviewed-by: Connie Wan <connily@chromium.org>
Commit-Queue: Charlene Yan <cyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773941}

chrome/browser/ui/views/tabs/tab_strip.cc

@@ -2892,18 +2892,20 @@ void TabStrip::ShiftTabRelative(Tab* tab, int offset) {
     return;
   }
 
-  // If the tab is at a group boundary, instead of actually moving the tab just
-  // change its group membership.
+  // If the tab is at a group boundary and the group is expanded, instead of
+  // actually moving the tab just change its group membership.
   base::Optional<tab_groups::TabGroupId> target_group =
       tab_at(target_index)->group();
   if (tab->group() != target_group) {
-    if (tab->group().has_value())
+    if (tab->group().has_value()) {
       controller_->RemoveTabFromGroup(start_index);
-    else if (target_group.has_value())
+      return;
+    } else if (target_group.has_value() &&
+               !controller_->IsGroupCollapsed(target_group.value())) {
       controller_->AddTabToGroup(start_index, target_group.value());
-
       return;
     }
+  }
 
   controller_->MoveTab(start_index, target_index);
 }