How can I resize the too big Open File dialog in OSX?

TL;DR: Shift-Cmd drag from left or right edge of the dialog window.

The problem is that the top of the dialog doesn't have a resize handle. However, the left and right sides of the dialog do have resize handles. That means that you constrain the aspect ratio of the dialog and resize from the left or right, and the bottom will resize proportionally.

You can use Shift+Cmd drag on either the left or right edge of the dialog and it will resize the entire window, bringing the bottom into view.

Swap the main window to Fullscreen, then the dialog should automatically resize to fit, sufficient to reach the bottom & lift it up further.

Then out of Fullscreen it will remember that size.

Option/drag doesn't work on sheets that are attached to the underlying window, unfortunately.

Separate issue: not remembering the window position

Quit Chrome.
Go to ~/Library/Saved Application State/com.google.Chrome.savedState
Trash the entire com.google.Chrome.savedState folder

Stumbled upon a solution! click the V button next to the file name box - this cycles reduce-enlarging the window, showing the cancel button. On second click, the window opens to the proper size, showing filenames in the folder and the Cancel or Save buttons.