In bug 740194 it was brought up that using [[MDCPalette greyPalette] tint500] text on white background can have too little contrast. Approximate measurements in https://crbug.com/740194#c5 seem to confirm that tint600 instead of tint500 needs to be used to achieve the 4.5:1 minimum contrast ratio required by accessibility standards.

The tint500 grey is used consistently across Chrome's UI on iOS, e.g., for detailedText of CollectionViewTextItem. What we need to do:

(1) Verify properly the contrast of the currently used grey-on-white.
(2) If needed, increase the tint of grey to reach the ratio of 4.5:1.