Add key modifier on minimize/restore button click to minimize/restore all Panels for Mac.

chrome/browser/ui/panels/panel.h

Index: chrome/browser/ui/panels/panel.h
diff --git a/chrome/browser/ui/panels/panel.h b/chrome/browser/ui/panels/panel.h
index 2a92fafed8b70cedd73d8749137ee0440b61273f..a86818933b47f33a4506c2afdf8d124319d246c3 100644
--- a/chrome/browser/ui/panels/panel.h
+++ b/chrome/browser/ui/panels/panel.h
@@ -219,9 +219,11 @@ class Panel : public BrowserWindow,
                                         const gfx::Rect& bounds);
 
   // Invoked when the native panel has detected a mouse click on the
-  // panel's titlebar. Behavior of the click may be modified as
-  // indicated by |modifier|.
+  // panel's titlebar, minimize or restore buttons. Behavior of the
+  // click may be modified as indicated by |modifier|.
   void OnTitlebarClicked(panel::ClickModifier modifier);
+  void OnMinimizeButtonClicked(panel::ClickModifier modifier);
+  void OnRestoreButtonClicked(panel::ClickModifier modifier);
 
   // Used on platforms where the panel cannot determine its window size
   // until the window has been created. (e.g. GTK)