Move ContentVideoCaptureDeviceCore from src/content to src/media

content/browser/media/capture/feedback_signal_accumulator.cc

-// Copyright (c) 2015 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 "content/browser/media/capture/feedback_signal_accumulator.h"
-
-#include <algorithm>
-#include <cmath>
-
-namespace content {
-
-FeedbackSignalAccumulator::FeedbackSignalAccumulator(base::TimeDelta half_life)
-    : half_life_(half_life) {
-  DCHECK(half_life_ > base::TimeDelta());
-}
-
-void FeedbackSignalAccumulator::Reset(double starting_value,
-                                      base::TimeTicks timestamp) {
-  DCHECK(!timestamp.is_null());
-  average_ = update_value_ = prior_average_ = starting_value;
-  reset_time_ = update_time_ = prior_update_time_ = timestamp;
-}
-
-bool FeedbackSignalAccumulator::Update(double value,
-                                       base::TimeTicks timestamp) {
-  DCHECK(!reset_time_.is_null());
-
-  if (timestamp < update_time_) {
-    return false;  // Not in chronological order.
-  } else if (timestamp == update_time_) {
-    if (timestamp == reset_time_) {
-      // Edge case: Multiple updates at reset timestamp.
-      average_ = update_value_ = prior_average_ =
-          std::max(value, update_value_);
-      return true;
-    }
-    if (value <= update_value_)
-      return true;
-    update_value_ = value;
-  } else {
-    prior_average_ = average_;
-    prior_update_time_ = update_time_;
-    update_value_ = value;
-    update_time_ = timestamp;
-  }
-
-  const double elapsed_us =
-      static_cast<double>((update_time_ - prior_update_time_).InMicroseconds());
-  const double weight = elapsed_us / (elapsed_us + half_life_.InMicroseconds());
-  average_ = weight * update_value_ + (1.0 - weight) * prior_average_;
-  DCHECK(std::isfinite(average_));
-
-  return true;
-}
-
-}  // namespace content