Implement break signal for serial api.

`Break` is somewhat related to control signaling and holds tx line low for n milliseconds.
Adding platform specific implementation.

BUG=461169
TEST=Manual with attached application on crbug.com/461169

Review URL: https://codereview.chromium.org/1128943005

Cr-Commit-Position: refs/heads/master@{#334111}

device/serial/serial_io_handler.h

@@ -83,6 +83,14 @@ class SerialIoHandler : public base::NonThreadSafe,
   // successfully retrieved.
   virtual serial::ConnectionInfoPtr GetPortInfo() const = 0;
 
+  // Initiates a BREAK signal. Places the transmission line in a break state
+  // until the |ClearBreak| is called.
+  virtual bool SetBreak() = 0;
+
+  // Terminates the BREAK signal. Places the transmission line in a nonbreak
+  // state.
+  virtual bool ClearBreak() = 0;
+
  protected:
   explicit SerialIoHandler(
       scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner,

device/serial/serial_io_handler_posix.cc

@@ -472,6 +472,23 @@ serial::ConnectionInfoPtr SerialIoHandlerPosix::GetPortInfo() const {
   return info.Pass();
 }
 
+bool SerialIoHandlerPosix::SetBreak() {
+  if (ioctl(file().GetPlatformFile(), TIOCSBRK, 0) != 0) {
+    VPLOG(1) << "Failed to set break";
+    return false;
+  }
+
+  return true;
+}
+
+bool SerialIoHandlerPosix::ClearBreak() {
+  if (ioctl(file().GetPlatformFile(), TIOCCBRK, 0) != 0) {
+    VPLOG(1) << "Failed to clear break";
+    return false;
+  }
+  return true;
+}
+
 std::string SerialIoHandler::MaybeFixUpPortName(const std::string& port_name) {
   return port_name;
 }

device/serial/serial_io_handler_posix.h

@@ -26,6 +26,8 @@ class SerialIoHandlerPosix : public SerialIoHandler,
   bool SetControlSignals(
       const serial::HostControlSignals& control_signals) override;
   serial::ConnectionInfoPtr GetPortInfo() const override;
+  bool SetBreak() override;
+  bool ClearBreak() override;
   void RequestAccess(
       const std::string& port,
       scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,

device/serial/serial_io_handler_win.cc

@@ -391,6 +391,22 @@ serial::ConnectionInfoPtr SerialIoHandlerWin::GetPortInfo() const {
   return info.Pass();
 }
 
+bool SerialIoHandlerWin::SetBreak() {
+  if (!SetCommBreak(file().GetPlatformFile())) {
+    VPLOG(1) << "Failed to set break";
+    return false;
+  }
+  return true;
+}
+
+bool SerialIoHandlerWin::ClearBreak() {
+  if (!ClearCommBreak(file().GetPlatformFile())) {
+    VPLOG(1) << "Failed to clear break";
+    return false;
+  }
+  return true;
+}
+
 std::string SerialIoHandler::MaybeFixUpPortName(const std::string& port_name) {
   // For COM numbers less than 9, CreateFile is called with a string such as
   // "COM1". For numbers greater than 9, a prefix of "\\\\.\\" must be added.

device/serial/serial_io_handler_win.h

@@ -27,6 +27,8 @@ class SerialIoHandlerWin : public SerialIoHandler,
   bool SetControlSignals(
       const serial::HostControlSignals& control_signals) override;
   serial::ConnectionInfoPtr GetPortInfo() const override;
+  bool SetBreak() override;
+  bool ClearBreak() override;
   bool PostOpen() override;
 
  private:

device/serial/test_serial_io_handler.cc

@@ -101,6 +101,14 @@ bool TestSerialIoHandler::SetControlSignals(
   return true;
 }
 
+bool TestSerialIoHandler::SetBreak() {
+  return true;
+}
+
+bool TestSerialIoHandler::ClearBreak() {
+  return true;
+}
+
 TestSerialIoHandler::~TestSerialIoHandler() {
 }
 

device/serial/test_serial_io_handler.h

@@ -32,6 +32,8 @@ class TestSerialIoHandler : public SerialIoHandler {
   serial::ConnectionInfoPtr GetPortInfo() const override;
   bool Flush() const override;
   bool SetControlSignals(const serial::HostControlSignals& signals) override;
+  bool SetBreak() override;
+  bool ClearBreak() override;
 
   serial::ConnectionInfo* connection_info() { return &info_; }
   serial::DeviceControlSignals* device_control_signals() {

extensions/browser/api/serial/serial_api.cc

@@ -422,6 +422,53 @@ void SerialSetControlSignalsFunction::Work() {
   results_ = serial::SetControlSignals::Results::Create(success);
 }
 
+SerialSetBreakFunction::SerialSetBreakFunction() {
+}
+
+SerialSetBreakFunction::~SerialSetBreakFunction() {
+}
+
+bool SerialSetBreakFunction::Prepare() {
+  params_ = serial::SetBreak::Params::Create(*args_);
+  EXTENSION_FUNCTION_VALIDATE(params_.get());
+
+  return true;
+}
+
+void SerialSetBreakFunction::Work() {
+  SerialConnection* connection = GetSerialConnection(params_->connection_id);
+  if (!connection) {
+    error_ = kErrorSerialConnectionNotFound;
+    return;
+  }
+  bool success = connection->SetBreak();
+  results_ = serial::SetBreak::Results::Create(success);
+}
+
+SerialClearBreakFunction::SerialClearBreakFunction() {
+}
+
+SerialClearBreakFunction::~SerialClearBreakFunction() {
+}
+
+bool SerialClearBreakFunction::Prepare() {
+  params_ = serial::ClearBreak::Params::Create(*args_);
+  EXTENSION_FUNCTION_VALIDATE(params_.get());
+
+  return true;
+}
+
+void SerialClearBreakFunction::Work() {
+  SerialConnection* connection = GetSerialConnection(params_->connection_id);
+  if (!connection) {
+    error_ = kErrorSerialConnectionNotFound;
+    return;
+  }
+
+  bool success = connection->ClearBreak();
+  results_ = serial::ClearBreak::Results::Create(success);
+}
+
 }  // namespace core_api
 
 }  // namespace extensions

extensions/browser/api/serial/serial_api.h

@@ -239,6 +239,38 @@ class SerialSetControlSignalsFunction : public SerialAsyncApiFunction {
   scoped_ptr<serial::SetControlSignals::Params> params_;
 };
 
+class SerialSetBreakFunction : public SerialAsyncApiFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("serial.setBreak", SERIAL_SETBREAK)
+  SerialSetBreakFunction();
+
+ protected:
+  ~SerialSetBreakFunction() override;
+
+  // AsyncApiFunction:
+  bool Prepare() override;
+  void Work() override;
+
+ private:
+  scoped_ptr<serial::SetBreak::Params> params_;
+};
+
+class SerialClearBreakFunction : public SerialAsyncApiFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("serial.clearBreak", SERIAL_CLEARBREAK)
+  SerialClearBreakFunction();
+
+ protected:
+  ~SerialClearBreakFunction() override;
+
+  // AsyncApiFunction:
+  bool Prepare() override;
+  void Work() override;
+
+ private:
+  scoped_ptr<serial::ClearBreak::Params> params_;
+};
+
 }  // namespace core_api
 
 }  // namespace extensions

extensions/browser/api/serial/serial_connection.cc

@@ -360,6 +360,14 @@ bool SerialConnection::SetControlSignals(
       *device::serial::HostControlSignals::From(control_signals));
 }
 
+bool SerialConnection::SetBreak() {
+  return io_handler_->SetBreak();
+}
+
+bool SerialConnection::ClearBreak() {
+  return io_handler_->ClearBreak();
+}
+
 void SerialConnection::OnReceiveTimeout() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   io_handler_->CancelRead(device::serial::RECEIVE_ERROR_TIMEOUT);

extensions/browser/api/serial/serial_connection.h

@@ -112,6 +112,12 @@ class SerialConnection : public ApiResource,
   bool SetControlSignals(
       const core_api::serial::HostControlSignals& control_signals);
 
+  // Suspend character transmission. Known as setting/sending 'Break' signal.
+  bool SetBreak();
+
+  // Restore character transmission. Known as clear/stop sending 'Break' signal.
+  bool ClearBreak();
+
   // Overrides |io_handler_| for testing.
   void SetIoHandlerForTest(scoped_refptr<device::SerialIoHandler> handler);
 

extensions/browser/extension_function_histogram_value.h

@@ -1111,6 +1111,8 @@ enum HistogramValue {
   PRINTERPROVIDERINTERNAL_REPORTUSBPRINTERINFO,
   WEBCAMPRIVATE_OPENSERIALWEBCAM,
   WEBCAMPRIVATE_CLOSEWEBCAM,
+  SERIAL_SETBREAK,
+  SERIAL_CLEARBREAK,
   // Last entry: Add new entries above and ensure to update
   // tools/metrics/histograms/histograms.xml.
   ENUM_BOUNDARY

extensions/common/api/serial.idl

@@ -171,6 +171,10 @@ namespace serial {
 
   callback FlushCallback = void (boolean result);
 
+  callback SetBreakCallback = void (boolean result);
+
+  callback ClearBreakCallback = void (boolean result);
+
   // The set of control signals which may be sent to a connected serial device
   // using <code>setControlSignals</code>. Note that support for these signals
   // is device-dependent.
@@ -307,6 +311,16 @@ namespace serial {
     static void setControlSignals(long connectionId,
                                   HostControlSignals signals,
                                   SetControlSignalsCallback callback);
+
+    // Suspends character transmission on a given connection and places the
+    // transmission line in a break state until the clearBreak is called.
+    // |connectionId| : The id of the connection.
+    static void setBreak(long connectionId, SetBreakCallback callback);
+
+    // Restore character transmission on a given connection and place the
+    // transmission line in a nonbreak state.
+    // |connectionId| : The id of the connection.
+    static void clearBreak(long connectionId, ClearBreakCallback callback);
   };
 
   interface Events {

tools/metrics/histograms/histograms.xml

@@ -54360,6 +54360,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="1050" label="PRINTERPROVIDERINTERNAL_REPORTUSBPRINTERINFO"/>
   <int value="1051" label="WEBCAMPRIVATE_OPENSERIALWEBCAM"/>
   <int value="1052" label="WEBCAMPRIVATE_CLOSEWEBCAM"/>
+  <int value="1053" label="SERIAL_SETBREAK"/>
+  <int value="1054" label="SERIAL_CLEARBREAK"/>
 </enum>
 
 <enum name="ExtensionInstallCause" type="int">