They don't enable access outside the sandbox and should be pretty safe. PPB_Testing_Dev is a set of helpers for writing tests: querying status of the plugin; r

They don't enable access outside the sandbox and should be pretty safe. PPB_Testing_Dev is a set of helpers for writing tests: querying status of the plugin; running nested message loop to wait for results of async operations; simulate input events which are received only by the plugin itself. PPB_Ext_Events_Dev is for registering/unregistering events provided by Chrome apps apis (http://developer.chrome.com/apps/api_index.html http://developer.chrome.com/apps/api_index.html). It will only be accessible when the NaCl module is included in a Chrome app. This interface hasn't been implemented yet.