Reland "Open MessagePumpLibevent's pipe with O_CLOEXEC"

base/files/file_util.h

Index: base/files/file_util.h
diff --git a/base/files/file_util.h b/base/files/file_util.h
index 420dcaee61b4ff0936b1189c6dc9e0ecb0369de7..81a60d794c0559ce9e203a9410e87f1eed9fa1f7 100644
--- a/base/files/file_util.h
+++ b/base/files/file_util.h
@@ -365,6 +365,17 @@ BASE_EXPORT int GetUniquePathNumber(const FilePath& path,
 BASE_EXPORT bool SetNonBlocking(int fd);
 
 #if defined(OS_POSIX)
+// Creates a non-blocking, close-on-exec pipe.
+// This creates a non-blocking pipe that is not intended to be shared with any
+// child process. This will be done atomically if the operating system supports
+// it. Returns true if it was able to create the pipe, otherwise false.
+BASE_EXPORT bool CreateLocalNonBlockingPipe(int fds[2]);
+
+// Sets the given |fd| to close-on-exec mode.
+// Returns true if it was able to set it in the close-on-exec mode, otherwise
+// false.
+BASE_EXPORT bool SetCloseOnExec(int fd);
+
 // Test that |path| can only be changed by a given user and members of
 // a given set of groups.
 // Specifically, test that all parts of |path| under (and including) |base|: