Implementation and fixes for Blimp client/engine E2E communication.

blimp/net/common.h

Index: blimp/net/common.h
diff --git a/blimp/net/common.h b/blimp/net/common.h
index 971644e1dfcb173ad91a3dc6999bef076320ce3a..29231042557a634d77d6607d03450a25f7e8ea19 100644
--- a/blimp/net/common.h
+++ b/blimp/net/common.h
@@ -10,6 +10,7 @@
 #include <string>
 
 #include "blimp/net/blimp_net_export.h"
+#include "net/base/ip_address_number.h"
 
 namespace blimp {
 
@@ -20,6 +21,10 @@ class BlimpMessage;
 extern const size_t BLIMP_NET_EXPORT kMaxPacketPayloadSizeBytes;
 extern const size_t BLIMP_NET_EXPORT kPacketHeaderSizeBytes;
 
+// Serializes human-readable BlimpMessage header info, for logging purposes.
+BLIMP_NET_EXPORT std::ostream& operator<<(std::ostream& out,
+                                          const BlimpMessage& message);
+
 }  // namespace blimp
 
 #endif  // BLIMP_NET_COMMON_H_