Cleanup: Mark some CrOS resources as platform-specific.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
===================================================================
--- chrome/app/generated_resources.grd	(revision 266144)
+++ chrome/app/generated_resources.grd	(working copy)
@@ -9672,9 +9672,6 @@
         <message name="IDS_HELP_TITLE" desc="Label used for title of the help page.">
           Help
         </message>
-        <message name="IDS_WEBKIT" desc="The name of the WebKit project; should not require translation.">
-          WebKit
-        </message>
         <message name="IDS_SHOW_MORE_INFO" desc="The label of the 'More info' link.">
           More info...
         </message>
@@ -9725,6 +9722,12 @@
         <message name="IDS_ABOUT_PRODUCT_VERSION" desc="The text label describing the version of the browser">
           Version <ph name="PRODUCT_VERSION">$1<ex>15.0.865.0</ex></ph>
         </message>
+      </if> <!-- not is_android -->
+
+      <if expr="chromeos">
+        <message name="IDS_WEBKIT" desc="The name of the WebKit project; should not require translation.">
+          WebKit
+        </message>
         <message name="IDS_ABOUT_PAGE_FIRMWARE" desc="Label used for Chrome OS bios firmware version.">
           Firmware
         </message>
@@ -9791,7 +9794,7 @@
         <message name="IDS_ABOUT_PAGE_CHANNEL_CHANGE_PAGE_CANCEL_BUTTON" desc="The label for the button for cancelling channel change.">
           Cancel
         </message>
-      </if>
+      </if> <!-- chromeos -->
 
       <message name="IDS_PLATFORM_LABEL" desc="Label for Platform">
         Platform