UserAgent: Mozilla/5.0 (X11; CrOS x86_64 8743.25.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.24 Safari/537.36
Platform: 8743.25.0 (Official Build) beta-channel monroe

Steps to reproduce the problem:
1. Open a folder from Google Drive in Google Chrome browser
2. Open the same folder from Google Drive in Files app
3. Open a PDF file in Google Chrome (all works fine)
4. Open the same PDF file in Files app (Google Chrome is failed to show this file in pdfium plugin).

What is the expected behavior?
Files app in Chrome OS should be able to open PDF files properly.

What went wrong?
Files app unable to open PDF files.

Did this work before? Yes This works three days before now.

Chrome version: 54.0.2840.24  Channel: beta
OS Version: 8743.25.0
Flash Version: Shockwave Flash 23.0 r0

The reproduction steps are shown in this video:
https://youtu.be/By8JQ5UFuD8