This change adds new CefCommandHandler callbacks for optionally hiding
specific Chrome toolbar icons, buttons and app menu items.
To test: Run `cefclient --enable-chrome-runtime --filter-chrome-commands`.
Most icons, buttons and app/context menu items will be hidden.
This change adds a CefCommandHandler::OnChromeCommand callback for optionally
handling Chrome commands triggered via menus or keyboard shortcuts. Supported
command IDs are listed in a new cef_command_ids.h header file.
To test: Run `cefclient --enable-chrome-runtime --hide-controls`. Most commands
will blocked and removed from context menus.
Marshall Greenblatt