Get tab information from Google Chrome in C/Go - c

Question

I'd like to gather some info on Google Chrome when it's running. Currently I'm doing this using some applescript (https://gist.github.com/jcla1/6525572), but I'd like to rewrite this in C or Go.
Does anyone know of an API Chrome exposes to gather information like:
# open tabs
current active URL
So far I've only found out that I can get the current tab's title using CGWindowListCopyWindowInfo (Carbon), which works well but obviously doesn't provide the URL (and not the # open tabs, etc.).
Ideally Chrome would have a event architecture which I could hook into and receive all the events to do with entering a new URL.
P.S. Only required to work on OSX!

Answer 1

I have written Go programs to remotely control/inspect chrome using the Remote Debugging Protocol. The way it works is you first fetch JSON data from a specific url and it gives the open tabs and basic information such as the tab's current url. You can then use the websocket links in the JSON object to contorl/inspect individual tabs.
Since you only want basic information, you can ignore most of the debugging api and just download the JSON index. Frist, start chrome using chrome --remote-debugging-port=9222. Note that all chrome windows need to be closed for this to work. You may also use --user-data-dir=<some dir> to launch with a fresh profile so you can leave your other chrome windows open.
Once you have the port open, obtaining the data is easy. Just go to http://localhost:9222/json and unmarshal the data. Here is the code I used :
type Tab struct {
Description string `json:"description"`
DevtoolsFrontendUrl string `json:"devtoolsFrontendUrl"`
FaviconUrl string `json:"faviconUrl"`
Id string `json:"id"`
ThumbnailUrl string `json:"thumbnailUrl"`
Title string `json:"title"`
Type string `json:"type"`
Url string `json:"url"`
WebSocketDebuggerUrl string `json:"webSocketDebuggerUrl"`
}
func GetTabs() ([]Tab, error) {
resp, err := http.Get("http://localhost:9222/json")
if err != nil {
return nil, err
}
defer resp.Body.Close()
var tabs []Tab
err = json.NewDecoder(resp.Body).Decode(&tabs)
if err != nil {
return nil, err
}
return tabs, nil
}
You can obtain more information here.
There is unfortunately no way to receive an event when a new tab is opened using this API. However, you can get notified when a tab you are connected to with websockets changes in any way. If you are willing to go crazy, you can build an extension to monitor for changes such as new tabs and loaded urls.