Add ScopedTaskSuspend and its test

util/posix/scoped_fcntl_flags.h

+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CRASHPAD_UTIL_POSIX_SCOPED_FCNTL_FLAGS_H_
+#define CRASHPAD_UTIL_POSIX_SCOPED_FCNTL_FLAGS_H_
+
+#include "base/basictypes.h"
+
+namespace crashpad {
+
+//! \brief Sets file descriptor status flags in the manner of `fcntl(F_SETFL,
+//!     …)` and resets them to their original value upon destruction.
+class ScopedFcntlFlags {
+ public:
+  ScopedFcntlFlags(int fd, int set_flags, int clear_flags);

[Robert Sesek, 2014/10/13 19:09:39]

Should document how |clear_flags| works.

+  ~ScopedFcntlFlags();
+
+ private:
+  int fd_;
+  int flags_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedFcntlFlags);
+};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_POSIX_SCOPED_FCNTL_FLAGS_H_