Getting Google+ profile picture url with user_id

Google had changed their policy so the old way for getting the Google profile image will not work now, which was

https://plus.google.com/s2/photos/profile/(user_id)?sz=150

New Way for doing this is

Request URL

https://www.googleapis.com/plus/v1/people/115950284...320?fields=image&key={YOUR_API_KEY}

That will give the Google profile image url in json format as given below

Response :

{
    "image": 
    {
         "url": "https://lh3.googleusercontent.com/-OkM...AANA/ltpH4BFZ2as/photo.jpg?sz=50"
    }
}

More parameters can be found to send with URL which you may need from here

For more detail you can also check the given question where I have answered for same type of problem How to get user image through user id in Google plus?

UPDATE: The method below DOES NOT WORK since 2015

It is possible to get the profile picture, and you can even set the size of it:

https://plus.google.com/s2/photos/profile/<user_id>?sz=<your_desired_size>

Example: My profile picture, with size set to 100 pixels:

https://plus.google.com/s2/photos/profile/116018066779980863044?sz=100

Usage with an image tag:

<img src="https://plus.google.com/s2/photos/profile/116018066779980863044?sz=100" width="100" height="100">

Hope you get it working!