Implemented ScopedFakeTime, faking rtc::TimeNanos.

webrtc/base/timeutils.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 12 matching lines @@
 #endif
 #include <windows.h>
 #include <mmsystem.h>
 #endif
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/timeutils.h"
 
 namespace rtc {
 
+namespace test {
+
+namespace {
+FakeTimeInterface* g_fake_time = nullptr;
+}  // Anonymous
+
+void SetFakeTime(FakeTimeInterface* fake_time) {
+  // Allow setting g_fake_time non-null only if old value is null.
+  if (fake_time)
+    RTC_CHECK(!g_fake_time);
+
+  g_fake_time = fake_time;
+}
+
+}  // namespace test
+
 uint64_t TimeNanos() {
+  if (test::g_fake_time)
+    return test::g_fake_time->TimeNanos();
+
   int64_t ticks = 0;
 #if defined(WEBRTC_MAC)
   static mach_timebase_info_data_t timebase;
   if (timebase.denom == 0) {
     // Get the timebase if this is the first time we run.
     // Recommended by Apple's QA1398.
     if (mach_timebase_info(&timebase) != KERN_SUCCESS) {
       RTC_DCHECK(false);
     }
   }
@@ skipping 117 matching lines @@
   if (expiry_in_leap_year && month <= 2 - 1) // |month| is zero based.
     day -= 1;
 
   // Combine all variables into seconds from 1970-01-01 00:00 (except |month|
   // which was accumulated into |day| above).
   return (((static_cast<int64_t>
             (year - 1970) * 365 + day) * 24 + hour) * 60 + min) * 60 + sec;
 }
 
 } // namespace rtc