Implement video frame acknowledgements in the chromoting protocol.

remoting/protocol/message_reader.h

Index: remoting/protocol/message_reader.h
diff --git a/remoting/protocol/message_reader.h b/remoting/protocol/message_reader.h
index 65d52d0a8bbe5cfb34965be2ef64eb982e8220e9..6b0eff279f94a7ac29b6b24816a6ca4db877e594 100644
--- a/remoting/protocol/message_reader.h
+++ b/remoting/protocol/message_reader.h
@@ -9,6 +9,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/non_thread_safe.h"
+#include "base/time/time.h"
 #include "remoting/base/compound_buffer.h"
 #include "remoting/protocol/message_decoder.h"
 
@@ -45,12 +46,19 @@ class MessageReader : public base::NonThreadSafe {
   // Starts reading from |socket|.
   void StartReading(net::Socket* socket);
 
+  // The time delta between first and last bytes of the last message for which
+  // MessageReceivedCallback has been invoked.
+  base::TimeDelta last_message_read_duration() {
+    return last_message_read_duration_;
+  }
+
  private:
   void DoRead();
   void OnRead(int result);
   void HandleReadResult(int result);
   void OnDataReceived(net::IOBuffer* data, int data_size);
-  void RunCallback(scoped_ptr<CompoundBuffer> message);
+  void RunCallback(scoped_ptr<CompoundBuffer> message,
+                   base::TimeDelta read_duration);
   void OnMessageDone();
 
   net::Socket* socket_;
@@ -72,6 +80,10 @@ class MessageReader : public base::NonThreadSafe {
   // Callback is called when a message is received.
   MessageReceivedCallback message_received_callback_;
 
+  // Used to track the time taken to receive each message.
+  base::TimeTicks last_message_started_time_;
+  base::TimeDelta last_message_read_duration_;
+
   base::WeakPtrFactory<MessageReader> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageReader);