Add interfaces for most major Blimp net components.

blimp/net/test_common.h

Index: blimp/net/test_common.h
diff --git a/blimp/net/test_common.h b/blimp/net/test_common.h
index 212715a8c8ebc00b0cd7ff9168e339335199a77b..4f027f85992c87a700dbe21d15365b6901701e8b 100644
--- a/blimp/net/test_common.h
+++ b/blimp/net/test_common.h
@@ -7,6 +7,7 @@
 
 #include <string>
 
+#include "blimp/net/blimp_message_processor.h"
 #include "net/socket/stream_socket.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
@@ -70,6 +71,17 @@ class MockStreamSocket : public net::StreamSocket {
   MOCK_CONST_METHOD0(GetTotalReceivedBytes, int64_t());
 };
 
+class MockBlimpMessageProcessor : public BlimpMessageProcessor {
+ public:
+  MockBlimpMessageProcessor();
+
+  ~MockBlimpMessageProcessor() override;
+
+  MOCK_METHOD2(ProcessMessage,
+               void(const BlimpMessage& message,
+                    const net::CompletionCallback& callback));
+};
+
 // Returns true if |buf| has a prefix of |str|.
 // Behavior is undefined if len(buf) < len(str).
 bool BufferStartsWith(net::GrowableIOBuffer* buf, const std::string& str);