Exclude ChromeOS directories from Mac coverage lines....

build/win/chrome_win.croc

 # -*- python -*-
 # Crocodile config file for Chromium windows
 
 {
   # List of rules, applied in order
   'rules' : [
     # Specify inclusions before exclusions, since rules are in order.
 
-    # Don't include posix or linux specific files
+    # Don't include chromeos, posix, or linux specific files
     {
-      'regexp' : '.*(_|/)(linux|posix)(\\.|_)',
+      'regexp' : '.*(_|/)(chromeos|linux|posix)(\\.|_)',
+      'include' : 0,
+    },
+    # Don't include ChromeOS dirs
+    {
+      'regexp' : '.*/chromeos/',
       'include' : 0,
     },
 
     # Groups
     {
       'regexp' : '.*_test_win\\.',
       'group' : 'test',
     },
   ],
 }