Chrome Version       : 48 (on Android only)
URLs (if applicable) :http://quirksmode.org/m/tests/fictitiousviewport.html
Other browsers tested: Safari iOS, IE10 Mobile (and lots of others, but they don't apply; see below)
  Add OK or FAIL, along with the version, after other browsers where you
have tested this issue:
     Safari iOS 8 and 9: OK
    Firefox: n/a
         IE 10 Mobile: OK

What steps will reproduce the problem?
1. Go to http://quirksmode.org/m/tests/fictitiousviewport.html
2. You should see a red, fixed element at the bottom of the screen
3. It's not there. In fact, it's off-screen.

What is the expected result?
The red, fixed element should be positioned at the bottom of the screen (or, more correctly, at the bottom of the layout viewport).

What happens instead?
The element is offscreen, at a number of pixels equivalent to the height of a fictitious viewport that is stretched up to accomodate a too-wide element present in the page but retains its aspect ratio. See the test page for an example calculation and a script that proves that this is the case.


Please provide any additional information below. Attach a screenshot if
possible.

This bug does not occur in Safari iOS and IE10 Mobile, the only two other browsers where fixed elements are positioned relative to the layout viewport. Other browsers, such as UC, BlackBerry, Firefox, as well as Chrome below 40, position it relative to the visual viewport, so there this bug cannot occur.

I confirmed the existence of this bug in Samsung Chromium 44. I suspect it was introduced along with the revised position: fixed handling in Chrome 40, but that's an educated guess.

Thanks - ppk