Implement serial API for Windows.

chrome/browser/extensions/api/serial/serial_port_enumerator_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/api/serial/serial_port_enumerator.h"
 
+#include "base/memory/scoped_ptr.h"
+#include "base/string_util.h"
+#include "base/stringprintf.h"
+
+#include <windows.h>
+
 namespace extensions {
 
 // static
-SerialPortEnumerator::StringSet SerialPortEnumerator::GenerateValidPatterns() {
-  // TODO(miket): implement
+SerialPortEnumerator::StringSet
+SerialPortEnumerator::GenerateValidPatterns() {
   StringSet valid_patterns;
   return valid_patterns;
 }
 
+static bool PassesCommConfigTest(const string16& port_name) {
+  COMMCONFIG comm_config;
+  DWORD cc_size = sizeof(COMMCONFIG);
+  return GetDefaultCommConfig(port_name.c_str(), &comm_config, &cc_size) ||
+      cc_size != sizeof(COMMCONFIG);
+}
+
 // static
 SerialPortEnumerator::StringSet
 SerialPortEnumerator::GenerateValidSerialPortNames() {
-  // TODO(miket): implement
-  StringSet valid_names;
-  return valid_names;
+  StringSet name_set;
+  int max_port_number = 16;
+
+  // We ended up not using valid_patterns. TODO(miket): we might want
+  // to refactor this interface to make it more platform-independent.
+  for (int port_number = 0; port_number < max_port_number; ++port_number) {
+    string16 device_string16 = (port_number <= 9) ?
+      base::StringPrintf(L"COM%d", port_number) :
+      base::StringPrintf(L"\\\\.\\COM%d", port_number);
+
+    if (PassesCommConfigTest(device_string16)) {
+      // Keep looking for new ports as long as we're finding them.
+      int new_max_port_number = (port_number + 1) * 2;
+      if (new_max_port_number > max_port_number)
+        max_port_number = new_max_port_number;
+
+      std::string device_string(WideToASCII(device_string16));
+      name_set.insert(device_string);
+    }
+  }
+  return name_set;
 }
 
 }  // namespace extensions