Add icon to the panel titlebar on Mac.

chrome/browser/ui/panels/panel_window_controller_cocoa.mm

Index: chrome/browser/ui/panels/panel_window_controller_cocoa.mm
diff --git a/chrome/browser/ui/panels/panel_window_controller_cocoa.mm b/chrome/browser/ui/panels/panel_window_controller_cocoa.mm
index 167c9058abd1dd3b94900914e6eae57edc0647a7..b6a8b2ce94225bf8b77f1a6237cd1f6043e435f4 100644
--- a/chrome/browser/ui/panels/panel_window_controller_cocoa.mm
+++ b/chrome/browser/ui/panels/panel_window_controller_cocoa.mm
@@ -20,6 +20,7 @@
 #import "chrome/browser/ui/cocoa/find_bar/find_bar_bridge.h"
 #import "chrome/browser/ui/cocoa/find_bar/find_bar_cocoa_controller.h"
 #import "chrome/browser/ui/cocoa/menu_controller.h"
+#import "chrome/browser/ui/cocoa/tab_contents/favicon_util.h"
 #include "chrome/browser/ui/panels/panel.h"
 #include "chrome/browser/ui/panels/panel_browser_window_cocoa.h"
 #include "chrome/browser/ui/panels/panel_manager.h"
@@ -178,6 +179,12 @@ static BOOL g_reportAnimationStatus = NO;
                                      withNewTitle:newTitle
                                         forWindow:[self window]]);
   [titlebar_view_ setTitle:newTitle];
+
+  NSImage* newIcon = mac::FaviconForTabContents(
+      windowShim_->browser()->GetSelectedTabContentsWrapper());
+  [titlebar_view_ setIcon:newIcon];
+
+  [titlebar_view_ updateIconAndTitleLayout];
 }
 
 - (void)addFindBar:(FindBarCocoaController*)findBarCocoaController {