Chrome内容菜单API上下文类型

I am looking at the API for chrome.contextMenu here.

The context types listed are:

• "all"
• "page"
• "frame"
• "selection"
• "link"
• "editable"
• "image"
• "video"
• "audio"
• "launcher"
• "browser_action"
• "page_action"

Some of these are intuitive, the others not so much.

Where can I find definitions for these different contexts? It is hard to make use of the api without this background knowledge.

Specifically, I would like to know "page", "frame", "editable", and "launcher".

• "link", "image", "video", "audio" are more or less self-explanatory; they correspond to right-clicks on the appropriate HTML elements.
• "editable" means a right-click in any text input element (when text is not selected, I think). It can be something obvious like <input>, <textarea> or any tag with content-editable enabled. This question may be of interest.
• "page" means a right-click on any space on the page that is not covered by the above.
• "all" is all of the above combined.
• "frame" is like "all", but only for content within <iframe>s and not the parent document. (source & rationale)
• "selection" means a right-click on a selected part of text/HTML; a text-only copy of the content will be passed to the callback, and a content script can be used to access the DOM of the selection.
• "browser_action" and "page_action" populate your icon's context menu when using Browser Actions and/or Page Actions.
• "launcher" only makes sense for Chrome Apps; it adds context menu entries to the App's shortcut in the App Launcher.