views: mac: Support dynamic resize of title bar height (see #3189)

This is intended for usage with frameless windows that show the standard window
buttons, where resizing the title bar height changes the button offset. Returning a
different value from CefWindowDelegate::GetTitlebarHeight and forcing a resize of
the NSWindow's theme frame (see ViewsWindow::NudgeWindow) will update the
title bar height.

To test:
1. Run `cefclient --use-views --hide-frame --show-window-buttons --url=http://tests/window`
2. Enter a new value for title bar height and click the "Set Titlebar Height" button

libcef/browser/views/view_util.h

@@ -9,7 +9,6 @@
 #include "include/views/cef_view.h"
 #include "include/views/cef_window.h"
 
-#include "third_party/abseil-cpp/absl/types/optional.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/views/view.h"
 
@@ -29,6 +28,8 @@ class NativeWidgetDelegate;
 }
 }  // namespace views
 
+class CefWindowDelegate;
+
 #define CEF_REQUIRE_VALID_RETURN(ret) \
   if (!ParentClass::IsValid())        \
     return ret;
@@ -148,9 +149,8 @@ CefWindowHandle GetWindowHandle(gfx::NativeWindow window);
 
 views::NativeWidget* CreateNativeWidget(
     views::internal::NativeWidgetDelegate* delegate,
-    bool is_frameless,
-    bool with_window_buttons,
-    absl::optional<float> title_bar_height);
+    CefRefPtr<CefWindow> window,
+    CefWindowDelegate* window_delegate);
 
 }  // namespace view_util