Cleanup to keep panel from manipulating its panel strip assignment directly.

chrome/browser/ui/panels/panel_overflow_browsertest.cc

Index: chrome/browser/ui/panels/panel_overflow_browsertest.cc
diff --git a/chrome/browser/ui/panels/panel_overflow_browsertest.cc b/chrome/browser/ui/panels/panel_overflow_browsertest.cc
index 7b50a7e72ff2b4cd5bfabb04a05d62134f493491..abe85c2833a103dc737a53835cfe68be2f77ddd2 100644
--- a/chrome/browser/ui/panels/panel_overflow_browsertest.cc
+++ b/chrome/browser/ui/panels/panel_overflow_browsertest.cc
@@ -254,9 +254,9 @@ IN_PROC_BROWSER_TEST_F(PanelOverflowBrowserTest, UpdateDraggableStatus) {
   PanelManager* panel_manager = PanelManager::GetInstance();
   Panel* panel = CreatePanel("panel");
   EXPECT_TRUE(panel->draggable());
-  panel->MoveToStrip(panel_manager->overflow_strip());
+  panel_manager->ChangePanelLayout(panel, PanelStrip::IN_OVERFLOW);
   EXPECT_FALSE(panel->draggable());
-  panel->MoveToStrip(panel_manager->docked_strip());
+  panel_manager->ChangePanelLayout(panel, PanelStrip::DOCKED);
   EXPECT_TRUE(panel->draggable());
   panel->Close();
 }