Make HSTS headers not clobber preloaded pins.

net/http/transport_security_state_unittest.cc

Index: net/http/transport_security_state_unittest.cc
diff --git a/net/http/transport_security_state_unittest.cc b/net/http/transport_security_state_unittest.cc
index 599bfb2b92c08e11327e6f50e4d17d671f6a2618..3d7d88f66ac40e97fa11c926b4763fab783e8e17 100644
--- a/net/http/transport_security_state_unittest.cc
+++ b/net/http/transport_security_state_unittest.cc
@@ -234,6 +234,17 @@ static bool OnlyPinning(const char *hostname) {
          !domain_state.ShouldUpgradeToSSL();
 }
 
+TEST_F(TransportSecurityStateTest, NoClobberPins) {
+  TransportSecurityState state;
+  TransportSecurityState::DomainState domain_state;
+
+  EXPECT_TRUE(state.GetDomainState("accounts.google.com", true, &domain_state));
+  EXPECT_TRUE(HasPublicKeyPins("accounts.google.com"));
+  EXPECT_TRUE(state.AddHSTSHeader("accounts.google.com",
+                                  "includesubdomains; max-age=1000000"));
+  EXPECT_TRUE(HasPublicKeyPins("accounts.google.com"));
+}
+
 TEST_F(TransportSecurityStateTest, Preloaded) {
   TransportSecurityState state;
   TransportSecurityState::DomainState domain_state;