Blink blocks all the non-scalable fonts), color or not. Currently, fontconfig treats any bitmap font as non-scalable.

As a result, Blink (used by Chrome and Opera) rejects color fonts in Google's proposed color bitmap font format (such as Noto Color Emoji). 

By treating color bitmap fonts as scalable, we can get 'Noto Color Emoji' and other color fonts in the same format to be accepted by Blink. 

An alternative is to change fontconfig to introduce 'FC_COLOR' and let clients such as Blink accept color fonts (bitmap or not). My patch for that is http://goo.gl/rDRffN

In the meantime, fontconfig on ChromeOS uses  the following addition to local.conf to treat Noto Color Emoji as scalable.  See http://crbug.com/386772#c15 

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>

  <match target="scan">
    <test name="family">
      <string>Noto Color Emoji</string>
    </test>
    <edit name="scalable" mode="assign">
      <bool>true</bool>
    </edit>
  </match>

  <match target="pattern">
    <test name="prgname">
      <string>chrome</string>
    </test>
    <edit name="family" mode="prepend_first">
      <string>Noto Color Emoji</string>
    </edit>
  </match>

</fontconfig>