Dear Shraddha,
Thank you for using the UCSC Genome Browser and your question about text based custom tracks from a file sharing source like Google Drives. Because external file sharing sites are always susceptible to changes it is hard to give lasting advice regarding the success of using such resources.
In the past by setting up a Google Drive Public Folder there has been success loading a custom track text file in the browser (not a google document, but rather a simple text file like the following:
https://9503d018e9a9ec6120cf35feff213ec3b7d639f8-www.googledrive.com/host/0B73lfGFqMGYuS3pKY25pbFpSREU). You can see more on this Google Drive support page:
https://support.google.com/drive/answer/2881970?hl=en, but it appears there is a note explaining the feature will be discontinued this August. The documentation on customTrackText.html will be updated.
Thank you again for your inquiry and using the UCSC Genome Browser. If you have any further questions, please reply to
gen...@soe.ucsc.edu. All messages sent to that address are archived on a publicly-accessible forum. If your question includes sensitive data, you may send it instead to
genom...@soe.ucsc.edu.
All the best,
Brian Lee
UCSC Genomics Institute