Fix BufferedSocketWriter to buffer everything before it starts writing.

remoting/protocol/channel_multiplexer.cc

Index: remoting/protocol/channel_multiplexer.cc
diff --git a/remoting/protocol/channel_multiplexer.cc b/remoting/protocol/channel_multiplexer.cc
index ecdf46279dc2d272a2819a3fb93bb42fa757c974..7625afbb2cdc446d17e2e4a0919ebd7350aa49bf 100644
--- a/remoting/protocol/channel_multiplexer.cc
+++ b/remoting/protocol/channel_multiplexer.cc
@@ -372,10 +372,10 @@ void ChannelMultiplexer::OnBaseChannelReady(
     reader_.StartReading(base_channel_.get(),
                          base::Bind(&ChannelMultiplexer::OnBaseChannelError,
                                     base::Unretained(this)));
-    writer_.Init(base::Bind(&P2PStreamSocket::Write,
-                            base::Unretained(base_channel_.get())),
-                 base::Bind(&ChannelMultiplexer::OnBaseChannelError,
-                            base::Unretained(this)));
+    writer_.Start(base::Bind(&P2PStreamSocket::Write,
+                             base::Unretained(base_channel_.get())),
+                  base::Bind(&ChannelMultiplexer::OnBaseChannelError,
+                             base::Unretained(this)));
   }
 
   DoCreatePendingChannels();