Unfortunately, I cannot reproduce.

1. Open directory A in a file picker in the regular mode.
2. Open incognito.
3. Open directory B in a file picker in incognito.
4. Close incognito.
5. Reopen incognito.
6. Open the file picker; it opens back in directory A.

This is true of both the file picker (i.e. <input type="file">) and of the "Save as..." downloads menu.

Is it possible that you just accidentally navigated to the 'secret' directory in the regular mode?

Sorry, I don't think I was completely clear before. It remembers location when choosing to upload a file in regular Chrome. 

Try this:
1. Open directory A in file picker regular mode. 
2. Open incognito 
3. Save file to directory B
4. Close incognito 
5. Close regular chrome (optional) 
6. Reopen regular chrome
7. Go to site with upload capability eg. Inbox.google.com
8. Compose new email
9. Clip paperclip to attach file
10. Choose, select file from computer 
11. *Directory B shown*

Thanks! I managed to reproduce it now.

My reproduction steps referred to a different bug that I believe had been fixed in the past, but your steps indeed revealed another problem.

We couldn't reproduce it on Linux but the same issue exists on Mac.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

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This sounds very similar to https://crbug.com/484003. I will mark as blocking to check if this is solved when the other issue has been fixed.

It seems that this only happens if the open dialog in regular mode is "Multi file". The reproduction steps in this bug and 484003 both refer to websites that open multiple files. Can you reproduce it in another situation?

I've already filed a bug for that:  crbug.com/831097 

Not sure there are different modes of these dialogues. What I am seeing is simply that Chrome remembers the last location of file operation in incognito, both download and upload.

Like I, in an incognito window,
1. click the "Attach a file" here below and choose example.jpg from D:\Temp,
2. next time I invoke a file opening dialogue, either via a file uploading interface or simply Ctrl+O, the dialogue will start at D:\Temp, persistently.

I am not the original reporter though.

Thank you for the comment.
There are two mode of open dialogues, one for selecting a single file, and another for selecting multiple files. As far as I see in the code (and manual tests), only the multiple-file-select dialogue had this problem.

I mean, this scenario should be persistent now:
1. Opening a file in regular mode from directory A.
2. Opening a file in incognito mode from directory B.
3. Opening a file in normal mode using single-file-select dialogue (like attache a file here).

But this one was NOT persistent and is now fixed in  crbug.com/831097 :
1. Opening a file in regular mode from directory A.
2. Opening a file in incognito mode from directory B.
3. Opening a file in normal mode using multi-file-select dialogoue (like jpg2pdf.com).

Marking fixed as crrev.com/c/1005079 is landed.

Thanks for the explanation. I can confirm with the current Dev version which does not have your fix yet and with a fresh profile, all work as you elaborated.

However, I come to realize my profile is in a rare condition causing a separate issue that serves as an exception, and leads to my previous comment which is not true with a fresh profile.

The fact is that after a fresh Chrome installation, I never invoked a file opening dialogue in a regular window.
I use only incognito window (created a shortcut that has --incognito switch set permanently). Besides the settings pages that cannot be opened in incognito, I barely open a regular window.

I guess this result in the so-called initial folder is never being set (since it is designed to be set only by a regular window?), so wherever the location last opened serves as the initial folder next time, regardless the dialogue modes and the fact that it all operated in incognito.
(And the location is even being remembered across profiles. When I created a fresh profile via --user-data-dir to test your comment, I found the dialogue started with the last location I opened in my existing profile which again, only operated in incognito all the time)

Nevertheless this is not really a problem for me and is apparently too scarce a use case to fix, unless the fix is super easy, I believe?

I guess the "if (!initial_path.empty())" part is the issue here. The fix only works if you ever used the file selector in regular mode before, otherwise Chrome doesn't know which directory it should use and the operating system decides to use the last opened directory (from incognito). Could we set a default value for initial_path? 

Yes, you are right. This is still a bug. Reopening.

 Issue 154613  has been merged into this issue.

 Issue 124960  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/69ea529b50030be6464c6f4c577baff7a88cfe05

commit 69ea529b50030be6464c6f4c577baff7a88cfe05
Author: Ramin Halavati <rhalavati@chromium.org>
Date: Tue Apr 24 12:30:01 2018

Set user's home directory as last selected directory of new profiles.

New profiles' last selected file directory was left uninitialized, and
hence the first file open was done in the last OS selected directory.
This created unpredicted behavior for new profiles, and could cause
leakage of the last folder used in incognito mode.
User's home directory is now set as the default value for it.

Bug:  659632 
Change-Id: I91e49e7152bda9abe26ff97ece12f08f9805c8de
Reviewed-on: https://chromium-review.googlesource.com/1023401
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553058}
[modify] https://crrev.com/69ea529b50030be6464c6f4c577baff7a88cfe05/chrome/browser/profiles/profile.cc
[modify] https://crrev.com/69ea529b50030be6464c6f4c577baff7a88cfe05/chrome/browser/profiles/profile_browsertest.cc

The above CL has fixed it. Now:

1- When a profile is created, it's "last used directory" is set to user's home directory.
2- Incognito profiles have a separate last used directory, so doesn't interfere with regular mode. 
3- Last used directory is used for all types of file open dialogs.