Move OnCursorChange from CefRenderHandler to CefDisplayHandler

The cursor change can now be handled by the client with both windowed and
off-screen rendering.

Returning true from OnCursorChange will disable the default cursor change
behavior. This is functionally equivalent to the
CefBrowserHost::SetMouseCursorChangeDisabled method, so that method has been
removed.

libcef/browser/native/cursor_util_linux.cc

@@ -0,0 +1,33 @@
+// Copyright 2020 The Chromium Embedded Framework Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "libcef/browser/native/cursor_util.h"
+
+#include "ui/base/cursor/cursor_factory.h"
+
+#if defined(USE_X11)
+#include "ui/base/x/x11_cursor.h"
+#endif
+
+namespace cursor_util {
+
+cef_cursor_handle_t GetPlatformCursor(ui::mojom::CursorType type) {
+  auto cursor = ui::CursorFactory::GetInstance()->GetDefaultCursor(type);
+  if (cursor) {
+    return ToCursorHandle(*cursor);
+  }
+  return 0;
+}
+
+cef_cursor_handle_t ToCursorHandle(ui::PlatformCursor cursor) {
+#if defined(USE_X11)
+  // See https://crbug.com/1029142 for background.
+  return static_cast<cef_cursor_handle_t>(
+      static_cast<ui::X11Cursor*>(cursor)->xcursor());
+#else
+  return cursor;
+#endif
+}
+
+}  // namespace cursor_util