Google Chrome	71.0.3558.0 (Official Build) dev (64-bit)
Firmware Version	Google_Caroline.7820.384.0

Steps to reproduce:
# Download a .docx, .xlsx, or .pptx file (I created these by using "Download as" from Google Docs/Sheets/Slides)
# Open it locally in Chrome OS out of files, opening the Office Editing extension
# Examine all of the icons that are grayed out such as redo, undo, merge cells, and drawing and fill tools
Expected: color contrast sufficient with background
Actual: color contrast too low

Foreground: #AAA9A9
Background: #F3F3F3
Contrast ratio: 2.11:1