views: Support styling of menus (issue #2102)

tests/cefclient/browser/client_handler.h

@@ -38,7 +38,8 @@ class ClientHandler : public CefClient,
                       public CefRequestHandler {
  public:
   // Implement this interface to receive notification of ClientHandler
-  // events. The methods of this class will be called on the main thread.
+  // events. The methods of this class will be called on the main thread unless
+  // otherwise indicated.
   class Delegate {
    public:
     // Called when the browser is created.
@@ -74,6 +75,9 @@ class ClientHandler : public CefClient,
     // Set focus to the next/previous control.
     virtual void OnTakeFocus(bool next) {}
 
+    // Called on the UI thread before a context menu is displayed.
+    virtual void OnBeforeContextMenu(CefRefPtr<CefMenuModel> model) {}
+
    protected:
     virtual ~Delegate() {}
   };