Move IN_OVERFLOW from Panel::ExpansionState to new enum.

chrome/browser/ui/panels/panel_overflow_strip.cc

Index: chrome/browser/ui/panels/panel_overflow_strip.cc
diff --git a/chrome/browser/ui/panels/panel_overflow_strip.cc b/chrome/browser/ui/panels/panel_overflow_strip.cc
index d56bcd4886096b9f8950f371f80b2c728a83ca30..9609896e6c4bbfa2ec3a78f50d8c02b5ffcae369 100644
--- a/chrome/browser/ui/panels/panel_overflow_strip.cc
+++ b/chrome/browser/ui/panels/panel_overflow_strip.cc
@@ -81,7 +81,7 @@ void PanelOverflowStrip::UpdateCurrentWidth() {
 void PanelOverflowStrip::AddPanel(Panel* panel) {
   // TODO(jianli): consider using other container to improve the perf for
   // inserting to the front. http://crbug.com/106222
-  DCHECK_EQ(Panel::IN_OVERFLOW, panel->expansion_state());
+  DCHECK_EQ(Panel::IN_OVERFLOW, panel->strip_owner());
   // Newly created panels that were temporarily in the panel strip
   // are added to the back of the overflow, whereas panels that are
   // bumped from the panel strip by other panels go to the front
@@ -146,9 +146,10 @@ void PanelOverflowStrip::RemoveAll() {
     (*iter)->Close();
 }
 
-void PanelOverflowStrip::OnPanelExpansionStateChanged(Panel* panel) {
-  // Only care about new state being overflow.
-  if (panel->expansion_state() != Panel::IN_OVERFLOW)
+void PanelOverflowStrip::OnPanelStripOwnerChanged(Panel* panel,
+                                                  Panel::StripOwner old_owner) {
+  // Only care about new owner being overflow.
+  if (panel->strip_owner() != Panel::IN_OVERFLOW)
     return;
 
   panel_manager_->panel_strip()->Remove(panel);
@@ -158,7 +159,7 @@ void PanelOverflowStrip::OnPanelExpansionStateChanged(Panel* panel) {
 }
 
 void PanelOverflowStrip::OnPanelAttentionStateChanged(Panel* panel) {
-  DCHECK(panel->expansion_state() == Panel::IN_OVERFLOW);
+  DCHECK_EQ(Panel::IN_OVERFLOW, panel->strip_owner());
   UpdateOverflowIndicatorAttention();
 }