[BattOr] Retry battor_agent commands when they fail.

tools/battor_agent/battor_connection_impl.cc

Index: tools/battor_agent/battor_connection_impl.cc
diff --git a/tools/battor_agent/battor_connection_impl.cc b/tools/battor_agent/battor_connection_impl.cc
index 0677ea08155a6b1cb9b824e91479bcb4c80aaf34..e3dfa2df282e7eda11fef5d694c7320628d1800b 100644
--- a/tools/battor_agent/battor_connection_impl.cc
+++ b/tools/battor_agent/battor_connection_impl.cc
@@ -80,6 +80,8 @@ BattOrConnectionImpl::~BattOrConnectionImpl() {}
 
 void BattOrConnectionImpl::Open() {
   if (io_handler_) {
+    // Opening new connection so flush serial data from old connection.
+    Flush();

[rnephew (Reviews Here), 2017/05/09 15:04:06]

Are the flushes not needed elsewhere because we moved it here?

[aschulman, 2017/05/11 13:13:00]

Correct. Before we had to flush manually between retries of specific messages
(e.g., INIT). Now when a command fails it will reopen the BattOr connection
which will then jump into this condition and Flush() the existing connection.

     OnOpened(true);
     return;
   }