Add a Clock and TickClock interface for mocking out time

media/base/clock.cc

 // Copyright (c) 2012 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.
 
 #include "media/base/clock.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
+#include "base/time/clock.h"
 #include "media/base/buffers.h"
 
 namespace media {
 
-Clock::Clock(TimeProvider* time_provider)
-    : time_provider_(time_provider) {
+Clock::Clock(base::Clock* clock) : clock_(clock) {
+  DCHECK(clock_);
   Reset();
 }
 
 Clock::~Clock() {}
 
 bool Clock::IsPlaying() const {
   return playing_;
 }
 
 base::TimeDelta Clock::Play() {
@@ skipping 62 matching lines @@
     max_time_ = ClampToValidTimeRange(max_time_);
 }
 
 base::TimeDelta Clock::ElapsedViaProvidedTime(const base::Time& time) const {
   // TODO(scherkus): floating point badness scaling time by playback rate.
   int64 now_us = (time - reference_).InMicroseconds();
   now_us = static_cast<int64>(now_us * playback_rate_);
   return media_time_ + base::TimeDelta::FromMicroseconds(now_us);
 }
 
-base::Time Clock::GetTimeFromProvider() const {
-  if (time_provider_)
-    return time_provider_();
-  return base::Time();
-}
-
 base::TimeDelta Clock::ClampToValidTimeRange(base::TimeDelta time) const {
   if (duration_ == kNoTimestamp())
     return base::TimeDelta();
   return std::max(std::min(time, duration_), base::TimeDelta());
 }
 
 void Clock::EndOfStream() {
   Pause();
   SetTime(Duration(), Duration());
 }
 
 base::TimeDelta Clock::Duration() const {
   if (duration_ == kNoTimestamp())
     return base::TimeDelta();
   return duration_;
 }
 
 void Clock::UpdateReferencePoints() {
   UpdateReferencePoints(Elapsed());
 }
 
 void Clock::UpdateReferencePoints(base::TimeDelta current_time) {
   media_time_ = ClampToValidTimeRange(current_time);
-  reference_ = GetTimeFromProvider();
+  reference_ = clock_->Now();
 }
 
 base::TimeDelta Clock::EstimatedElapsedTime() {
-  return ClampToValidTimeRange(
-      ElapsedViaProvidedTime(GetTimeFromProvider()));
+  return ClampToValidTimeRange(ElapsedViaProvidedTime(clock_->Now()));
 }
 
 void Clock::Reset() {
   playing_ = false;
   playback_rate_ = 1.0f;
   max_time_ = kNoTimestamp();
   duration_ = kNoTimestamp();
   media_time_ = base::TimeDelta();
   reference_ = base::Time();
   underflow_ = false;
 }
 
 }  // namespace media