Adds a DCHECK that the host argument to QuicInMemoryCache::AddResponse is not empty. An empty host …

net/tools/quic/quic_in_memory_cache.cc

Index: net/tools/quic/quic_in_memory_cache.cc
diff --git a/net/tools/quic/quic_in_memory_cache.cc b/net/tools/quic/quic_in_memory_cache.cc
index fd77050b49e91ccb6f6c680e4cef27e71a287a27..21efe0a709cc900b8d48da586685dc691803e35a 100644
--- a/net/tools/quic/quic_in_memory_cache.cc
+++ b/net/tools/quic/quic_in_memory_cache.cc
@@ -204,6 +204,7 @@ void QuicInMemoryCache::AddResponseImpl(
     const SpdyHeaderBlock& response_headers,
     StringPiece response_body,
     const SpdyHeaderBlock& response_trailers) {
+  DCHECK(!host.empty()) << "Host must be populated, e.g. \"www.google.com\"";
   string key = GetKey(host, path);
   if (ContainsKey(responses_, key)) {
     LOG(DFATAL) << "Response for '" << key << "' already exists!";