Add mojo/c/system/{time.h,wait.h}.

mojo/public/c/system/time.h

+// Copyright 2016 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.
+
+// This file contains Mojo system time-related declarations/definitions.
+//
+// Note: This header should be compilable as C.
+
+#ifndef MOJO_PUBLIC_C_SYSTEM_TIME_H_
+#define MOJO_PUBLIC_C_SYSTEM_TIME_H_
+
+#include <stdint.h>
+
+// |MojoTimeTicks|: A time delta, in microseconds, the meaning of which is
+// source-dependent.
+
+typedef int64_t MojoTimeTicks;
+
+// |MojoDeadline|: Used to specify deadlines (timeouts), in microseconds (except
+// for |MOJO_DEADLINE_INDEFINITE|).
+//   |MOJO_DEADLINE_INDEFINITE| - Used to indicate "forever".
+
+typedef uint64_t MojoDeadline;
+
+#define MOJO_DEADLINE_INDEFINITE ((MojoDeadline)-1)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Note: Pointer parameters that are labelled "optional" may be null (at least
+// under some circumstances). Non-const pointer parameters are also labeled
+// "in", "out", or "in/out", to indicate how they are used. (Note that how/if
+// such a parameter is used may depend on other parameters or the requested
+// operation's success/failure. E.g., a separate |flags| parameter may control
+// whether a given "in/out" parameter is used for input, output, or both.)
+
+// Returns the time, in microseconds, since some undefined point in the past.
+// The values are only meaningful relative to other values that were obtained
+// from the same device without an intervening system restart. Such values are
+// guaranteed to be monotonically non-decreasing with the passage of real time.
+// Although the units are microseconds, the resolution of the clock may vary and
+// is typically in the range of ~1-15 ms.
+MojoTimeTicks MojoGetTimeTicksNow(void);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // MOJO_PUBLIC_C_SYSTEM_TIME_H_