Google Chrome	69.0.3473.0 (Official Build) dev (64-bit)
Firmware Version Google_Lulu.6301.136.57

Steps to repro:
# Enable docked magnifier via settings or search + ctrl + d
# Put focus into the Omnibox ensuring the blue focus ring appears around it or that there is a blue focus highlight on the content of the box. It doesn't matter if there are search suggestions showing.
# Move the mouse elsewhere on the screen, for example, the Docs logo in the shelf, and hover the mouse until the tool tip appears. 
Expected: nothing happens, magnifier still tracks mouse until keyboard is invoked
Actual: upon tool tip being shown, docked magnifier focus moves to the Omnibox  

This does not happen if the keyboard focus is anywhere else, just in the Omnibox.
This also does not happen with the fullscreen magnifier. Since the default keyboard focus upon launching a new tab is in the Omnibox, it could be more prevalent than if this occurred in other places.