Use sockets with unread data if they've never been used before.

net/socket/socks5_client_socket.cc

Index: net/socket/socks5_client_socket.cc
diff --git a/net/socket/socks5_client_socket.cc b/net/socket/socks5_client_socket.cc
index 004b67c669fe0c949500c4eb8eb1a50ea47ef126..ce96c1d5a4412d0d53b5aa97dafda424d021b1ff 100644
--- a/net/socket/socks5_client_socket.cc
+++ b/net/socket/socks5_client_socket.cc
@@ -5,6 +5,7 @@
 #include "net/socket/socks5_client_socket.h"
 
 #include "base/basictypes.h"
+#include "base/callback_helpers.h"
 #include "base/compiler_specific.h"
 #include "base/debug/trace_event.h"
 #include "base/format_macros.h"
@@ -38,6 +39,7 @@ SOCKS5ClientSocket::SOCKS5ClientSocket(
       bytes_sent_(0),
       bytes_received_(0),
       read_header_size(kReadHeaderSize),
+      was_used_to_convey_data_(false),
       host_request_info_(req_info),
       net_log_(transport_->socket()->NetLog()) {
 }
@@ -109,11 +111,7 @@ void SOCKS5ClientSocket::SetOmniboxSpeculation() {
 }
 
 bool SOCKS5ClientSocket::WasEverUsed() const {
-  if (transport_.get() && transport_->socket()) {
-    return transport_->socket()->WasEverUsed();
-  }
-  NOTREACHED();
-  return false;
+  return was_used_to_convey_data_;
 }
 
 bool SOCKS5ClientSocket::UsingTCPFastOpen() const {
@@ -157,7 +155,13 @@ int SOCKS5ClientSocket::Read(IOBuffer* buf, int buf_len,
   DCHECK_EQ(STATE_NONE, next_state_);
   DCHECK(user_callback_.is_null());
 
-  return transport_->socket()->Read(buf, buf_len, callback);
+  int rv = transport_->socket()->Read(
+      buf, buf_len,
+      base::Bind(&SOCKS5ClientSocket::OnReadWriteComplete,
+                 base::Unretained(this), callback));
+  if (rv > 0)
+    was_used_to_convey_data_ = true;
+  return rv;
 }
 
 // Write is called by the transport layer. This can only be done if the
@@ -168,7 +172,13 @@ int SOCKS5ClientSocket::Write(IOBuffer* buf, int buf_len,
   DCHECK_EQ(STATE_NONE, next_state_);
   DCHECK(user_callback_.is_null());
 
-  return transport_->socket()->Write(buf, buf_len, callback);
+  int rv = transport_->socket()->Write(
+      buf, buf_len,
+      base::Bind(&SOCKS5ClientSocket::OnReadWriteComplete,
+                 base::Unretained(this), callback));
+  if (rv > 0)
+    was_used_to_convey_data_ = true;
+  return rv;
 }
 
 bool SOCKS5ClientSocket::SetReceiveBufferSize(int32 size) {
@@ -185,9 +195,7 @@ void SOCKS5ClientSocket::DoCallback(int result) {
 
   // Since Run() may result in Read being called,
   // clear user_callback_ up front.
-  CompletionCallback c = user_callback_;
-  user_callback_.Reset();
-  c.Run(result);
+  base::ResetAndReturn(&user_callback_).Run(result);
 }
 
 void SOCKS5ClientSocket::OnIOComplete(int result) {
@@ -199,6 +207,16 @@ void SOCKS5ClientSocket::OnIOComplete(int result) {
   }
 }
 
+void SOCKS5ClientSocket::OnReadWriteComplete(const CompletionCallback& callback,
+                                            int result) {

[mmenke, 2014/03/18 15:16:55]

nit:  Fix indent

[davidben, 2014/03/25 19:50:18]

Done.

+  DCHECK_NE(ERR_IO_PENDING, result);
+  DCHECK(!callback.is_null());

[mmenke, 2014/03/18 15:16:55]

Seems weird to have this DCHECK here, and not in Read or Write.  So I suggest
also putting it in those two functions (Same for the other SOCKS socket class)

[davidben, 2014/03/25 19:50:18]

Done.

+
+  if (result > 0)
+    was_used_to_convey_data_ = true;
+  callback.Run(result);
+}
+
 int SOCKS5ClientSocket::DoLoop(int last_io_result) {
   DCHECK_NE(next_state_, STATE_NONE);
   int rv = last_io_result;