Add MachMessageWithDeadline() and supporting characters

util/mach/mach_message_test.cc

Index: util/mach/mach_message_test.cc
diff --git a/util/mach/mach_message_test.cc b/util/mach/mach_message_test.cc
index b807b7ed5205f098b788936f56cf0616d61ba18c..eed6c8e21820deaef30e10a2100bef89e7546c39 100644
--- a/util/mach/mach_message_test.cc
+++ b/util/mach/mach_message_test.cc
@@ -22,6 +22,20 @@ namespace crashpad {
 namespace test {
 namespace {
 
+TEST(MachMessage, MachMessageDeadlineFromTimeout) {
+  MachMessageDeadline deadline_0 = MachMessageDeadlineFromTimeout(0);
+  EXPECT_EQ(kMachMessageNonblocking, deadline_0);
+
+  deadline_0 = MachMessageDeadlineFromTimeout(1);
+  MachMessageDeadline deadline_1 = MachMessageDeadlineFromTimeout(100);
+
+  EXPECT_NE(kMachMessageNonblocking, deadline_0);
+  EXPECT_NE(kMachMessageWaitIndefinitely, deadline_0);
+  EXPECT_NE(kMachMessageNonblocking, deadline_1);
+  EXPECT_NE(kMachMessageWaitIndefinitely, deadline_1);
+  EXPECT_GE(deadline_1, deadline_0);
+}
+
 TEST(MachMessage, PrepareMIGReplyFromRequest_SetMIGReplyError) {
   mach_msg_header_t request;
   request.msgh_bits =