Fixes another places that may trigger deletion during tab dragging

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

Index: chrome/browser/ui/views/tabs/tab_drag_controller.cc
diff --git a/chrome/browser/ui/views/tabs/tab_drag_controller.cc b/chrome/browser/ui/views/tabs/tab_drag_controller.cc
index bb452ef74e862ee346469916b96e9bb59ec622df..15d382e1935f1342865a78d2e6545465770fd2e4 100644
--- a/chrome/browser/ui/views/tabs/tab_drag_controller.cc
+++ b/chrome/browser/ui/views/tabs/tab_drag_controller.cc
@@ -1543,6 +1543,9 @@ void TabDragController::RunMoveLoop(const gfx::Vector2d& drag_offset) {
       // Move the tabs into position.
       MoveAttached(point_in_screen);
       attached_tabstrip_->GetWidget()->Activate();
+      // Activate may trigger a focus loss, destroying us.
+      if (!ref)
+        return;
       tab_strip_to_attach_to_after_exit_ = NULL;
     }
     DCHECK(attached_tabstrip_);