chromeos: Add OS credits link to about page.

chrome/app/chromium_strings.grd

Index: chrome/app/chromium_strings.grd
diff --git a/chrome/app/chromium_strings.grd b/chrome/app/chromium_strings.grd
index 2d86fa22554dbb547ec46469f4a05c88cc58cb5a..5be20ceaec6f7a23518d37413805f0bb5db03c30 100644
--- a/chrome/app/chromium_strings.grd
+++ b/chrome/app/chromium_strings.grd
@@ -199,6 +199,11 @@ be available for now. -->
       <message name="IDS_ABOUT_VERSION_LICENSE" desc="The label below the copyright message, containing the URLs.">
         Chromium is made possible by the <ph name="BEGIN_LINK_CHROMIUM">BEGIN_LINK_CHR</ph>Chromium<ph name="END_LINK_CHROMIUM">END_LINK_CHR</ph> open source project and other <ph name="BEGIN_LINK_OSS">BEGIN_LINK_OSS</ph>open source software<ph name="END_LINK_OSS">END_LINK_OSS</ph>.
       </message>
+      <if expr="pp_ifdef('chromeos')">
+        <message name="IDS_ABOUT_CROS_VERSION_LICENSE" desc="Additional text displayed beneath the Chromium open source URLs for Chromium OS.">
+          Chromium OS is made possible by additional <ph name="BEGIN_LINK_CROS_OSS">BEGIN_LINK_CROS_OSS</ph>open source software<ph name="END_LINK_CROS_OSS">END_LINK_CROS_OSS</ph>.
+        </message>
+      </if>
       <message name="IDS_ABOUT_TERMS_OF_SERVICE" desc="The terms of service label in the About box.">
         Not used in Chromium. Placeholder to keep resource maps in synch.
       </message>