Chrome Version       : 53.0.2750.0
URLs (if applicable) : Any. For instance, browser://help
OS version               : MacOS X 10.11
Behavior in Chrome for Windows: Not tested yet, because I have no such touchpad with gestures on my Windows PC.

Steps to reproduce:

(1) Zoom in using touchpad gesture (stretch with two fingers) to the maximum magnification

  Expected: the page is zoomed, the icon (+) appears in the location bar, the percentage in the app menu changes.
  Observed: the page is zoomed, but there is no icon, and the percentage is 100%

(2) Go to the app menu and click [+] button.
  Expected: no more zoom, as we already have reached its limit.
  Observed: even greater zoom.

(3) Click [+] and [-] buttons there.
  Expected: zoom percentage increases/decreases to the absolute value shown in the app menu and in the popup of the (+) icon.
  Observed: zoom increases/decreases relatively. But the indicator shows fake percentage - relative to 100%.

(4) Click the (+) icon, then click "Reset" button on the popup.
  Expected: zoom resets to 100%, the indicator shows 100%, the icon disappears.
  Observed: yes, it works.