chrome: Improve positioning of the "Find" widget (fixes #3461)

The "Find" widget will be excluded from regions near the edges of the window
that contain overlays, draggable regions or titlebar.

libcef/browser/browser_platform_delegate.cc

@@ -241,6 +241,9 @@ std::unique_ptr<CefMenuRunner> CefBrowserPlatformDelegate::CreateMenuRunner() {
   return nullptr;
 }
 
+void CefBrowserPlatformDelegate::UpdateFindBarBoundingBox(
+    gfx::Rect* bounds) const {}
+
 bool CefBrowserPlatformDelegate::IsWindowless() const {
   return false;
 }