Handle |public| in check_gn_headers.py

build/check_gn_headers_unittest.py

Index: build/check_gn_headers_unittest.py
diff --git a/build/check_gn_headers_unittest.py b/build/check_gn_headers_unittest.py
index f62fe62309548d5c53803a0e2c6791e29c7cb668..1074d8856da49c3135b62ba268014698e8acd786 100755
--- a/build/check_gn_headers_unittest.py
+++ b/build/check_gn_headers_unittest.py
@@ -38,6 +38,7 @@ gn_input = json.loads(r'''
       "//:All": {
       },
       "//:base": {
+         "public": [ "//base/p.h" ],
          "sources": [ "//base/a.cc", "//base/a.h", "//base/b.hh" ],
          "visibility": [ "*" ]
       }
@@ -88,6 +89,7 @@ class CheckGnHeadersTest(unittest.TestCase):
     expected = set([
         'base/a.h',
         'base/b.hh',
+        'base/p.h',
     ])
     self.assertEquals(headers, expected)