This was happening to me for a long time. I changed my display picture in my Gmail and since then i was unable to view my own image in Gmail Chat window (contact list). However the Gmail shows the picture perfectly in the Settings page.
After searching the solution of this problem on Google, i found one trick and this worked for me. I am sharing this with you guys.
The problem seems to be with Gmail's new interface's image uploading system.
Step 1: Switch your Gmail to "Older Version" (from top right menu in Gamil).
Step 2: Now change your profile picture either using "Accounts Settings: or by Chat window. Save settings and cross check that the picture is visible in chat window.
Step 3: Now switch your Gmail interface to newer version again.
I hope this will help you.