[Tab Groups Collapse] Activate tab group header collapse by keyboard.

Bug: 1018230
Change-Id: I89f5f54b6e1083c7375b1b15f444a86b2a1269a1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225376
Commit-Queue: Charlene Yan <cyan@chromium.org>
Reviewed-by: Connie Wan <connily@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773936}

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

@@ -106,8 +106,14 @@ bool TabGroupHeader::OnKeyPressed(const ui::KeyEvent& event) {
   if ((event.key_code() == ui::VKEY_SPACE ||
        event.key_code() == ui::VKEY_RETURN) &&
       !editor_bubble_tracker_.is_open()) {
-    editor_bubble_tracker_.Opened(TabGroupEditorBubbleView::Show(
-        tab_strip_->controller()->GetBrowser(), group().value(), this));
+    if (base::FeatureList::IsEnabled(features::kTabGroupsCollapse)) {
+      // The collapse feature changes the behavior from showing the
+      // editor bubble to toggling the collapsed state of the group.
+      tab_strip_->controller()->ToggleTabGroupCollapsedState(group().value());
+    } else {
+      editor_bubble_tracker_.Opened(TabGroupEditorBubbleView::Show(
+          tab_strip_->controller()->GetBrowser(), group().value(), this));
+    }
     return true;
   }