Don't access .spec on a !is_valid PUSH_PROMISE URL.

net/spdy/spdy_session.cc

Index: net/spdy/spdy_session.cc
diff --git a/net/spdy/spdy_session.cc b/net/spdy/spdy_session.cc
index 92b8f5f34fcb1a2ec234a6ed2a807c3ae2a8725d..ca9a00ef5bf0fd6a13fff44369704430b97d21b4 100644
--- a/net/spdy/spdy_session.cc
+++ b/net/spdy/spdy_session.cc
@@ -2601,9 +2601,9 @@ void SpdySession::TryCreatePushStream(SpdyStreamId stream_id,
   // Verify that the response had a URL for us.
   GURL gurl = GetUrlFromHeaderBlock(headers);
   if (!gurl.is_valid()) {
-    EnqueueResetStreamFrame(stream_id, request_priority,
-                            ERROR_CODE_PROTOCOL_ERROR,
-                            "Pushed stream url was invalid: " + gurl.spec());
+    EnqueueResetStreamFrame(
+        stream_id, request_priority, ERROR_CODE_PROTOCOL_ERROR,
+        "Pushed stream url was invalid: " + gurl.possibly_invalid_spec());
     return;
   }