Disable PolicyTest.FileURLBlacklist on Mac since it's pretty flaky.

chrome/browser/policy/policy_browsertest.cc

Index: chrome/browser/policy/policy_browsertest.cc
diff --git a/chrome/browser/policy/policy_browsertest.cc b/chrome/browser/policy/policy_browsertest.cc
index e8e1a4a379a9d3683a9763f90cd2a109f01f3c0d..c7502c792a6b4c5a49d57033e257c413f390c511 100644
--- a/chrome/browser/policy/policy_browsertest.cc
+++ b/chrome/browser/policy/policy_browsertest.cc
@@ -2136,7 +2136,13 @@ IN_PROC_BROWSER_TEST_F(PolicyTest, URLBlacklist) {
   }
 }
 
-IN_PROC_BROWSER_TEST_F(PolicyTest, FileURLBlacklist) {
+#if defined(OS_MACOSX)
+// http://crbug.com/339240
+#define MAYBE_FileURLBlacklist DISABLED_FileURLBlacklist
+#else
+#define MAYBE_FileURLBlacklist FileURLBlacklist
+#endif
+IN_PROC_BROWSER_TEST_F(PolicyTest, MAYBE_FileURLBlacklist) {
   // Check that FileURLs can be blacklisted and DisabledSchemes works together
   // with URLblacklisting and URLwhitelisting.