cronet import: add url/third_party/mozilla

Test: run import -- see also aosp/2498638
Change-Id: I3df00ebf2a6e737d33783c3f7b9e438f33a46822
diff --git a/Cronet/tools/import/copy.bara.sky b/Cronet/tools/import/copy.bara.sky
index 8353fd3..ee4e5f1 100644
--- a/Cronet/tools/import/copy.bara.sky
+++ b/Cronet/tools/import/copy.bara.sky
@@ -98,6 +98,7 @@
         # Note: Only used for tests.
         "third_party/quic_trace/**",
         "third_party/zlib/**",
+        "url/third_party/mozilla/**",
     ],
     exclude = common_excludes,
 )