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

mojo/edk/platform/time_ticks.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.
 
 #ifndef MOJO_EDK_PLATFORM_TIME_TICKS_H_
 #define MOJO_EDK_PLATFORM_TIME_TICKS_H_
 
-#include "mojo/public/c/system/types.h"
+#include "mojo/public/c/system/time.h"
 
 namespace mojo {
 namespace platform {
 
 // Gets the number of microseconds elapsed since an undefined epoch. (This is
 // from a monotonic clock of undefined resolution.)
 //
 // Implementations of this function should be thread-safe. The returned value
 // should be non-negative, and nondecreasing with respect to time/causality
 // including across threads (as observable).
 //
 // TODO(vtl): Add different types of clocks. (What does "monotonic" mean exactly
 // -- does it continue to "run" in various "sleep" states?)
 MojoTimeTicks GetTimeTicks();
 
 }  // namespace platform
 }  // namespace mojo
 
 #endif  // MOJO_EDK_PLATFORM_TIME_TICKS_H_