Resurrect the cloud printer driver.

cloud_print/virtual_driver/win/port_monitor/BUILD.gn

Index: cloud_print/virtual_driver/win/port_monitor/BUILD.gn
diff --git a/cloud_print/virtual_driver/win/port_monitor/BUILD.gn b/cloud_print/virtual_driver/win/port_monitor/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..d3d8b63ed4a3697418405a9bffd2498c136c682c
--- /dev/null
+++ b/cloud_print/virtual_driver/win/port_monitor/BUILD.gn
@@ -0,0 +1,84 @@
+# Copyright 2015 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.
+
+import("//chrome/process_version_rc_template.gni")
+
+assert(is_win)
+
+# When cross-compiling a 64-bit driver for a 32-bit build, some things get name
+# mangled with this suffix.
+if (target_cpu == "x86" && current_cpu == "x64") {
+  arch_suffix = "64"
+} else {
+  arch_suffix = ""
+}
+
+# When compiling a 64-bit port monitor from a 32-bit build, copy the DLL to the
+# root build directory. When targeting 64-bit CPUs, there is no cross-compiling
+# so nothing extra needs to happen.
+if (target_cpu == "x86" && current_cpu == "x64") {
+  copy("port_monitor") {
+    sources = [
+      "$root_out_dir/gcp_portmon64.dll",
+    ]
+    outputs = [
+      "$root_build_dir/gcp_portmon64.dll",
+    ]
+    deps = [
+      ":port_monitor_dll",
+    ]
+  }
+} else {
+  group("port_monitor") {
+    public_deps = [
+      ":port_monitor_dll",
+    ]
+  }
+}
+
+shared_library("port_monitor_dll") {
+  output_name = "gcp_portmon$arch_suffix"
+
+  sources = [
+    "port_monitor.def",
+    "port_monitor_dll.cc",
+  ]
+
+  deps = [
+    ":lib",
+    ":resources",
+    "//base",
+    "//chrome/common:constants",
+    "//chrome/common:version_header",
+    "//cloud_print/common",
+    "//cloud_print/virtual_driver/win",
+  ]
+
+  libs = [ "userenv.lib" ]
+}
+
+source_set("lib") {
+  sources = [
+    "port_monitor.cc",
+    "port_monitor.h",
+  ]
+
+  deps = [
+    "//base",
+    "//chrome/common:constants",
+    "//chrome/installer/launcher_support",
+    "//cloud_print/common",
+    "//cloud_print/virtual_driver/win",
+  ]
+}
+
+process_version_rc_template("resources") {
+  sources = [
+    "../gcp_portmon${arch_suffix}_dll.ver",
+  ]
+
+  # Note: target_gen_dir will be different for each toolchain so the output
+  # name doesn't need mangling.
+  output = "$target_gen_dir/gcp_portmon_dll.rc"
+}