Add code to detect new added ReceiveError on Linux

device/serial/serial_io_handler_posix.h

Index: device/serial/serial_io_handler_posix.h
diff --git a/device/serial/serial_io_handler_posix.h b/device/serial/serial_io_handler_posix.h
index c9c5fb5416472c0d7edae75c630705cf2f3e49df..5050d2304fe21b3365b8c9c3ca3f25dac46389ae 100644
--- a/device/serial/serial_io_handler_posix.h
+++ b/device/serial/serial_io_handler_posix.h
@@ -12,6 +12,11 @@
 
 namespace device {
 
+// Linux reports breaks and parity errors by inserting the sequence '\377\0x'
+// into the byte stream where 'x' is '\0' for a break and the corrupted byte for
+// a parity error.
+enum class ErrorDetectState { NO_ERROR, MARK_377_SEEN, MARK_0_SEEN };
+
 class SerialIoHandlerPosix : public SerialIoHandler,
                              public base::MessageLoopForIO::Watcher {
  protected:
@@ -28,9 +33,15 @@ class SerialIoHandlerPosix : public SerialIoHandler,
   serial::ConnectionInfoPtr GetPortInfo() const override;
   bool SetBreak() override;
   bool ClearBreak() override;
+  int CheckReceiveError(char* buffer,
+                        int buffer_len,
+                        int bytes_read,
+                        bool& break_detected,
+                        bool& parity_error_detected);
 
  private:
   friend class SerialIoHandler;
+  friend class SerialIoHandlerPosixTest;
 
   SerialIoHandlerPosix(
       scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner,
@@ -51,6 +62,11 @@ class SerialIoHandlerPosix : public SerialIoHandler,
   bool is_watching_reads_;
   bool is_watching_writes_;
 
+  ErrorDetectState error_detect_state_;
+  bool parity_check_enabled_;
+  char chars_stashed_[2];
+  int num_chars_stashed_;
+
   DISALLOW_COPY_AND_ASSIGN(SerialIoHandlerPosix);
 };