Disable Quarantine tests on platforms its not supported.

content/common/quarantine/quarantine_linux.cc

Index: content/common/quarantine/quarantine_linux.cc
diff --git a/content/common/quarantine/quarantine_linux.cc b/content/common/quarantine/quarantine_linux.cc
index af207836d758758c495114eae6674f5bdad655e8..e66eaf27b18dde4ff59b7f9170d23cb817168b9f 100644
--- a/content/common/quarantine/quarantine_linux.cc
+++ b/content/common/quarantine/quarantine_linux.cc
@@ -10,6 +10,7 @@
 
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
+#include "base/files/scoped_temp_dir.h"
 #include "base/logging.h"
 #include "base/threading/thread_restrictions.h"
 #include "content/common/quarantine/quarantine_constants_linux.h"
@@ -96,4 +97,21 @@ bool IsFileQuarantined(const base::FilePath& file,
              referrer_url;
 }
 
+// Only to be used in tests.
+bool IsQuarantineSupportedForTesting() {

[bcf, 2017/01/06 20:43:00]

We should update quarantine_linux_unittest.cc to use this new function in
QuarantineLinuxTest::SetUp

+    base::ScopedTempDir temp_dir;
+    if (!temp_dir.CreateUniqueTempDir())
+      return false;
+
+    base::FilePath xattr_test_file;
+    if (!base::CreateTemporaryFileInDir(temp_dir.GetPath(), &xattr_test_file))
+      return false;
+
+    int result =
+        setxattr(xattr_test_file.value().c_str(), "user.test", "test", 4, 0);
+    bool is_xattr_supported = (!result) || (errno != ENOTSUP);
+
+    return is_xattr_supported;
+}
+
 }  // namespace content