Thanks for filing the issue!

@Reporter: As comment#0 was not very clear in understanding the issue i.e., auto re-loading of the page or asking for log-in every time when the page is refreshed...?, hence requesting you to elaborate on the same and please provide the test steps(...if any). Could you please check the same on a new profile without any apps & extensions and let us know if the issue still persists. 

Explain to you in simple words. In steps:
1). Open google chrome, click to Gmail
2). Enter my account detail and press sign in
3). My Gmail account opens
4). As soon as the open new email to read
5). Its get refreshed and a new page appears
6). And new pages ask to enter your Gmail account info to get a sign in.

Tried to explain as best I can do.

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Unable to reproduce the issue on chrome reported version# 69.0.3497.57 and on latest Beta# 69.0.3497.72 using Windows-7 & 10 as per steps mentioned in comment# 3.

@Reporter: Could you please try to test this issue by creating new person with no apps and extensions in it or test this issue on latest beta# 69.0.3497.72 and let us know if the issue still persists. You can download latest beta from URL: https://www.chromium.org/getting-involved/dev-channel.

Thanks!

Here are the few steps:
1. You need to go to the login window of Gmail.
2. When logged in, open any mail you want to read.
3. When you will click on "back" after reading you will have a refreshed window.
If you want to know more go to https://www.gmailtechnicalsupportnumbers.com/optimum-email-support/