Fix incorrect behavior in checking for TCP FastOpen platform support.

net/socket/tcp_socket_posix.cc

Index: net/socket/tcp_socket_posix.cc
diff --git a/net/socket/tcp_socket_posix.cc b/net/socket/tcp_socket_posix.cc
index 438d5aab41140a27ddf2cff6853c6253738a1be2..7ecdebd3bc39a95e155d7ba16563b0369877cdac 100644
--- a/net/socket/tcp_socket_posix.cc
+++ b/net/socket/tcp_socket_posix.cc
@@ -14,6 +14,8 @@
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/posix/eintr_wrapper.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
 #include "base/task_scheduler/post_task.h"
 #include "base/time/time.h"
 #include "net/base/address_list.h"
@@ -92,9 +94,12 @@ bool SystemSupportsTCPFastOpen() {
                               &system_supports_tcp_fastopen)) {
     return false;
   }
-  // The read from /proc should return '1' if TCP FastOpen is enabled in the OS.
+  // The read value from /proc will be set in its least significant bit if
+  // TCP FastOpen is enabled.
+  int read_int = 0;
   if (system_supports_tcp_fastopen.empty() ||
-      (system_supports_tcp_fastopen[0] != '1')) {
+      !StringToInt(StringPiece(system_supports_tcp_fastopen), &read_int) ||

[Randy Smith (Not in Mondays), 2017/02/23 15:15:32]

Are you comfortable with this failing if there's leading whitespace?  The
documentation indicates that it'll return false in those circumstances.

[Jana, 2017/02/24 19:24:44]

I've added whitespace trimming, PTAL.

+      (read_int & 0x1) != 1) {
     return false;
   }
   return true;