Update Panel mininimize/restore button on strip and expansion state change.

chrome/browser/ui/panels/panel_browser_window_cocoa.mm

Index: chrome/browser/ui/panels/panel_browser_window_cocoa.mm
diff --git a/chrome/browser/ui/panels/panel_browser_window_cocoa.mm b/chrome/browser/ui/panels/panel_browser_window_cocoa.mm
index 5c71ec13799a95f449272ce1bbfbff9e3f176bcf..4cc89185fa277898927cd6f60e91206f39cadea4 100644
--- a/chrome/browser/ui/panels/panel_browser_window_cocoa.mm
+++ b/chrome/browser/ui/panels/panel_browser_window_cocoa.mm
@@ -284,10 +284,6 @@ void PanelBrowserWindowCocoa::EnsurePanelFullyVisible() {
   [controller_ ensureFullyVisible];
 }
 
-void PanelBrowserWindowCocoa::SetPanelAppIconVisibility(bool visible) {
-  // TODO(dimich): to be implemented.
-}
-
 void PanelBrowserWindowCocoa::SetPanelAlwaysOnTop(bool on_top) {
   [controller_ updateWindowLevel];
 }
@@ -296,6 +292,10 @@ void PanelBrowserWindowCocoa::EnableResizeByMouse(bool enable) {
   [controller_ enableResizeByMouse:enable];
 }
 
+void PanelBrowserWindowCocoa::UpdatePanelMinimizeRestoreButtonVisibility() {
+  [controller_ updateTitleBarMinimizeRestoreButtonVisibility];
+}
+
 void PanelBrowserWindowCocoa::DidCloseNativeWindow() {
   DCHECK(!isClosed());
   panel_->OnNativePanelClosed();