Disable PnaclHeaderTest.TestHasPnaclHeader as it is flaky.

chrome/test/nacl/pnacl_header_test.cc

Index: chrome/test/nacl/pnacl_header_test.cc
diff --git a/chrome/test/nacl/pnacl_header_test.cc b/chrome/test/nacl/pnacl_header_test.cc
index e4922aa5867f96e9a8a3a069aee37c589b11546e..87727a949120bb308c26fcc2fe3b57422008652f 100644
--- a/chrome/test/nacl/pnacl_header_test.cc
+++ b/chrome/test/nacl/pnacl_header_test.cc
@@ -109,7 +109,8 @@ scoped_ptr<HttpResponse> PnaclHeaderTest::WatchForPexeFetch(
   return http_response.PassAs<HttpResponse>();
 }
 
-IN_PROC_BROWSER_TEST_F(PnaclHeaderTest, TestHasPnaclHeader) {
+// This test is flaky. See http://crbug.com/315328.
+IN_PROC_BROWSER_TEST_F(PnaclHeaderTest, DISABLED_TestHasPnaclHeader) {
   // Load 2 pexes, one same origin and one cross orgin.
   RunLoadTest("/nacl/pnacl_request_header/pnacl_request_header.html", 1, 1);
 }