Make dbus::FileDescriptor a Pass()-movable type.

dbus/file_descriptor.cc

Index: dbus/file_descriptor.cc
diff --git a/dbus/file_descriptor.cc b/dbus/file_descriptor.cc
index e607fc01356d8ca284f0ea1732150a0a43a3bf69..c67a9e1900bab2f3f737d2ecba4cab358d43eec2 100644
--- a/dbus/file_descriptor.cc
+++ b/dbus/file_descriptor.cc
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <algorithm>
+
 #include "base/bind.h"
 #include "base/files/file.h"
 #include "base/location.h"
@@ -9,6 +11,8 @@
 #include "base/threading/worker_pool.h"
 #include "dbus/file_descriptor.h"
 
+using std::swap;
+
 namespace dbus {
 
 void CHROME_DBUS_EXPORT FileDescriptor::Deleter::operator()(
@@ -17,11 +21,21 @@ void CHROME_DBUS_EXPORT FileDescriptor::Deleter::operator()(
       FROM_HERE, base::Bind(&base::DeletePointer<FileDescriptor>, fd), false);
 }
 
+FileDescriptor::FileDescriptor(RValue other)
+    : value_(-1), owner_(false), valid_(false) {
+  Swap(other.object);
+}
+
 FileDescriptor::~FileDescriptor() {
   if (owner_)
     base::File auto_closer(value_);
 }
 
+FileDescriptor& FileDescriptor::operator=(RValue other) {
+  Swap(other.object);
+  return *this;
+}
+
 int FileDescriptor::value() const {
   CHECK(valid_);
   return value_;
@@ -41,4 +55,10 @@ void FileDescriptor::CheckValidity() {
   valid_ = (ok && !info.is_directory);
 }
 
+void FileDescriptor::Swap(FileDescriptor* other) {
+  swap(value_, other->value_);
+  swap(owner_, other->owner_);
+  swap(valid_, other->valid_);
+}
+
 }  // namespace dbus