Remove parts of //cc we aren't using

cc/debug/frame_rate_counter.cc

-// Copyright 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 "cc/debug/frame_rate_counter.h"
-
-#include <algorithm>
-#include <limits>
-
-#include "base/metrics/histogram.h"
-#include "cc/trees/proxy.h"
-
-namespace cc {
-
-// The following constants are measured in seconds.
-
-// Two thresholds (measured in seconds) that describe what is considered to be a
-// "no-op frame" that should not be counted.
-// - if the frame is too fast, then given our compositor implementation, the
-// frame probably was a no-op and did not draw.
-// - if the frame is too slow, then there is probably not animating content, so
-// we should not pollute the average.
-static const double kFrameTooFast = 1.0 / 70.0;
-static const double kFrameTooSlow = 1.0 / 4.0;
-
-// If a frame takes longer than this threshold (measured in seconds) then we
-// (naively) assume that it missed a screen refresh; that is, we dropped a
-// frame.
-// TODO(brianderson): Determine this threshold based on monitor refresh rate,
-// crbug.com/138642.
-static const double kDroppedFrameTime = 1.0 / 50.0;
-
-// static
-scoped_ptr<FrameRateCounter> FrameRateCounter::Create(bool has_impl_thread) {
-  return make_scoped_ptr(new FrameRateCounter(has_impl_thread));
-}
-
-base::TimeDelta FrameRateCounter::RecentFrameInterval(size_t n) const {
-  DCHECK_GT(n, 0u);
-  DCHECK_LT(n, ring_buffer_.BufferSize());
-  return ring_buffer_.ReadBuffer(n) - ring_buffer_.ReadBuffer(n - 1);
-}
-
-FrameRateCounter::FrameRateCounter(bool has_impl_thread)
-    : has_impl_thread_(has_impl_thread), dropped_frame_count_(0) {}
-
-void FrameRateCounter::SaveTimeStamp(base::TimeTicks timestamp, bool software) {
-  ring_buffer_.SaveToBuffer(timestamp);
-
-  // Check if frame interval can be computed.
-  if (ring_buffer_.CurrentIndex() < 2)
-    return;
-
-  base::TimeDelta frame_interval_seconds =
-      RecentFrameInterval(ring_buffer_.BufferSize() - 1);
-
-  if (has_impl_thread_ && ring_buffer_.CurrentIndex() > 0) {
-    if (software) {
-      UMA_HISTOGRAM_CUSTOM_COUNTS(
-          "Renderer4.SoftwareCompositorThreadImplDrawDelay",
-          frame_interval_seconds.InMilliseconds(),
-          1,
-          120,
-          60);
-    } else {
-      UMA_HISTOGRAM_CUSTOM_COUNTS("Renderer4.CompositorThreadImplDrawDelay",
-                                  frame_interval_seconds.InMilliseconds(),
-                                  1,
-                                  120,
-                                  60);
-    }
-  }
-
-  if (!IsBadFrameInterval(frame_interval_seconds) &&
-      frame_interval_seconds.InSecondsF() > kDroppedFrameTime)
-    dropped_frame_count_ +=
-        frame_interval_seconds.InSecondsF() / kDroppedFrameTime;
-}
-
-bool FrameRateCounter::IsBadFrameInterval(
-    base::TimeDelta interval_between_consecutive_frames) const {
-  double delta = interval_between_consecutive_frames.InSecondsF();
-  bool scheduler_allows_double_frames = !has_impl_thread_;
-  bool interval_too_fast =
-      scheduler_allows_double_frames ? delta < kFrameTooFast : delta <= 0.0;
-  bool interval_too_slow = delta > kFrameTooSlow;
-  return interval_too_fast || interval_too_slow;
-}
-
-void FrameRateCounter::GetMinAndMaxFPS(double* min_fps, double* max_fps) const {
-  *min_fps = std::numeric_limits<double>::max();
-  *max_fps = 0.0;
-
-  for (RingBufferType::Iterator it = --ring_buffer_.End(); it; --it) {
-    base::TimeDelta delta = RecentFrameInterval(it.index() + 1);
-
-    if (IsBadFrameInterval(delta))
-      continue;
-
-    DCHECK_GT(delta.InSecondsF(), 0.f);
-    double fps = 1.0 / delta.InSecondsF();
-
-    *min_fps = std::min(fps, *min_fps);
-    *max_fps = std::max(fps, *max_fps);
-  }
-
-  if (*min_fps > *max_fps)
-    *min_fps = *max_fps;
-}
-
-double FrameRateCounter::GetAverageFPS() const {
-  int frame_count = 0;
-  double frame_times_total = 0.0;
-  double average_fps = 0.0;
-
-  // Walk backwards through the samples looking for a run of good frame
-  // timings from which to compute the mean.
-  //
-  // Slow frames occur just because the user is inactive, and should be
-  // ignored. Fast frames are ignored if the scheduler is in single-thread
-  // mode in order to represent the true frame rate in spite of the fact that
-  // the first few swapbuffers happen instantly which skews the statistics
-  // too much for short lived animations.
-  //
-  // IsBadFrameInterval encapsulates the frame too slow/frame too fast logic.
-
-  for (RingBufferType::Iterator it = --ring_buffer_.End();
-       it && frame_times_total < 1.0;
-       --it) {
-    base::TimeDelta delta = RecentFrameInterval(it.index() + 1);
-
-    if (!IsBadFrameInterval(delta)) {
-      frame_count++;
-      frame_times_total += delta.InSecondsF();
-    } else if (frame_count) {
-      break;
-    }
-  }
-
-  if (frame_count) {
-    DCHECK_GT(frame_times_total, 0.0);
-    average_fps = frame_count / frame_times_total;
-  }
-
-  return average_fps;
-}
-
-}  // namespace cc