Ah, it was the information that the expressions should be placed in the init file that I was missing.
I can confirm that I can reproduce the problem using the following recipe.
Place the following lines in a file, say bug22298.el:
(set-frame-size (selected-frame) 155 38 nil)
emacs -Q -l bug22298.el
Here, Emacs use its standard frame size whereas it should use the newly specified size (155x38).
-- Anders Lindgren
> Thank you for looking into this.
> In my bug report I listed two snippets that can be put into init.el.
> When (tool-bar-mode 1) is set before set-frame-size, it works. When set
> after set-frame-size, it won't.
> Using C-x C-e to eval them, it works. So I think "emacs -Q" can not help
> here. It's only about order of settings.
> Later after reporting, I found tool-bar-mode is defaulted to "t" when
> window-system is detected (in C source code), so I just removed it and
> it works now. So it does not bother me any more, but I can not say this
> bug is fixed.