Google Chrome OS 67.0.3369.0 (Official Build) canary (64-bit)
Firmware Version Google_Samus.6300.276.0

This affects users who want custom key mappings for both internal and external keyboards with Chromebooks. Use cases include attaching a Windows keyboard to the Chromebook via USB and changing the mappings on the internal keyboard to accommodate users who like Mac style keyboard layouts. 

Steps to repro for internal keyboard:
# Enable ChromeVox with ctrl + alt + z
# Go to Settings > Keyboard
# Change Search to the Alt
# Change Alt to be Search
# Attempt to linear navigate holding down the physical alt key (search) and the arrow keys
Expected: nav works
Actual: alt key is still treated as alt key, linear nav not working. The search key is still treated as a the search key. 

However, if ChromeVox is disabled, the system has switched the keys properly. Using the physical search key (alt) + ctrl + l will bring focus to the launcher.  While ChromeVox is enabled, the system isn't getting key commands for launcher, etc.

Steps for external keyboard are the same except the Caps Lock key should be set to Search. The same problems are present.