Make transport security state data source configurable.

net/http/transport_security_state.h

Index: net/http/transport_security_state.h
diff --git a/net/http/transport_security_state.h b/net/http/transport_security_state.h
index a55cf62d417cada4728bc7a810b4efb6980e8b17..5d3c126dcc2090015107eec88bc71ae0e9c3b7d7 100644
--- a/net/http/transport_security_state.h
+++ b/net/http/transport_security_state.h
@@ -19,6 +19,7 @@
 #include "net/base/expiring_cache.h"
 #include "net/base/hash_value.h"
 #include "net/base/net_export.h"
+#include "net/http/transport_security_state_source.h"
 #include "url/gurl.h"
 
 namespace net {
@@ -27,6 +28,9 @@ class HostPortPair;
 class SSLInfo;
 class X509Certificate;
 
+void NET_EXPORT_PRIVATE SetTransportSecurityStateSourceForTesting(
+    const TransportSecurityStateSource* source);
+
 // Tracks which hosts have enabled strict transport security and/or public
 // key pins.
 //