Google Drive files popup doesn't appear when attempting to open a file via 3rd-party website

[Eido95]

Description

Important to note: The issue resolve itself when disabling Brave Shields.

I want to open a file, which is stored on my Google Drive, via Xodo PDF Editor App, for editing purposes.

When clicking the Google Drive button, to browse the file from Google Drive, the Google Drive files explorer popup - not being shown.

Steps to Reproduce

1. Open Brave browser.
2. Navigate to https://www.xodo.com/app/.
3. Click on Google Drive button.

Actual result:

1. Nothing happens (Google Drive files explorer not being shown).
2. Error in JavaScript file seems to be thrown (build.js:37), so no actual requests are sent to Google Drive API (as seems in Developer tools Network tab).

Expected result:

1. Google Drive files explorer should be shown, and it will be possible to browse a file from Google Drive, to be opened via the Xodo App.
2. Requests should be sent to Google Drive API.

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

Brave: 0.58.21 Chromium: 71.0.3578.98 (Official Build) (64-bit)
Revision: 15234034d19b85dcd9a03b164ae89d04145d8368-refs/branch-heads/3578@{#897}
OS: Windows
JavaScript: V8 7.1.302.31
Flash: (Disabled)
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds?
  Didn't try that.

Website problems only:

• Does the issue resolve itself when disabling Brave Shields?
  Yes!
• Is the issue reproducible on the latest version of Chrome?
  No.

Additional Information

The issue resolve itself when disabling Brave Shields.

[srirambv]

Can you enabling all cookies from shields and check if it solves the issue?

[Eido95]

@srirambv, I tested what you requested.
Allowing all cookies from shields while shields are up, DID solve the issue.

[srirambv]

Reopening the issue and assigning to webcompat project.

[diracdeltas]

Almost certainly a 3rd party referer issue