Have independent histories for "Open" and "Save" dialogs

I noticed the "Save File" and the "Open File", at least on Chrome, are behaving in a "shared" state.

For example, if a webpage asks me to open a file, and I browse to `/home/me/xx/yy` directory to pick that file, when I click to "save as" another file (from the same or from another webpage) the dialog will ask me to save the file on that directory.

On the same way, if I save a file to `/home/me/Downloads`, when I click to upload a file on the browser, the dialog will put me on the same `/home/me/Downloads` directory.

The OPEN and the SAVE dialogs should have independent histories, since **saved files** mostly goes to `~/Downloads` and **opened files** are hardly picked from `~/Downloads`. Every other major distro/desktop environment has this split behavior for saving and opening files.

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