jidanni@ -- Thanks for reporting this issue. Could you please provide the sample file, screen cast reproducing the issue and expected result for the better understanding.

Also, please provide the device details where the issue is observed. This would help us in triaging the issue further.

Thanks in advance!

On a stock ASUS Zenfone 3, Android 8.0
in adb shell do
$ echo ABC一二三 > /sdcard/file.txt
Now open the stock File Manager app. There is only one.
Long press on /sdcard/file.txt .
You will see Open in Chrome Canary is one of the choices, choose it.
Now in Chrome Canary, do you see ABC一二三 or ABC and some garbled mess?
If you still see ABC一二三 then I will provide the actual file that caused the bug.

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

Tested on ASUS_Z00AD Android 5.0.0 by following the steps below:

1. Connected device under test to machine with adb confirgured.
2. Run the commands
adb shell
$ echo ABC一二三 > /sdcard/file.txt
3. File is generated in System Files.
4. Unfortunately there is no option "Open with" in mentioned device. Hence exported the file to Samsung J7 Android 7.0.0.
5. Opened the file in latest Canary #67.0.3369.0
6. Text displayed has some invalid content as here: ABC一二三

jidanni@ -- Could you please confirm wehther it is the actual issue or not.

Attached the screenshot and generated file.

Thanks!

Deleted: 820767-file.txt 13 bytes

820767-file.txt 13 bytes View Download

Deleted: 820767.png 28.4 KB

	820767.png 28.4 KB View Download

YES! This is the issue!
So... your mission is to allow users to view this file in Chrome with the correct character set!
Here we cannot blame the user for making an invalid file.
The file is a valid UTF-8 file.
Alas Chrome assumes all such files are Latin1... so it is clearly Chrome to blame!

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

Chrome must remember that not all files come over the network with HTTP headers.

In fact our local plain .txt file is the oldest such file in the history of computers. It is a  extreme shame that Chrome cannot open it properly.

Maybe Chrome thinks all oldest format files also have oldest Charsets too. Wrong!

Tested the issue in Android and able to reproduce the issue. Similar behavior is observed since Chrome #60.0.3072.0

Steps Followed:
1. Connected device under test to machine with adb confirgured.
2. Run the commands
adb shell
$ echo ABC一二三 > /sdcard/file.txt
3. File is generated in System Files.
4. Unfortunately there is no option "Open with" in mentioned device. Hence exported the file to Samsung J7 Android 7.0.0.
5. Opened the file in latest Canary #67.0.3369.0
6. Observed that text displayed has some invalid content as here: ABC一二三

Chrome versions tested:
60.0.3072.0, 65.0.3325.109(Stable), 67.0.3372.0(Canary)

OS:
Android 7.0.0

Android Devices:
Samsung J7

This seems to be a Non-Regression issue as same behavior is seen since M60.  Untriaged for further input's on this issue.

Please navigate to below link for log's, sample file generated and screen shot--
go/chrome-androidlogs/820767

Note - Similar issue is observed on FireFox mobile version.

Thanks!