Part 2 of cc/ directory shuffles: debug

Continuation of https://src.chromium.org/viewvc/chrome?view=rev&revision=188681

BUG=190824
TBR=enne@chromium.org

Review URL: https://codereview.chromium.org/12648008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@188685 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 57 insertions, 0 deletions

diff --git a/cc/debug/frame_rate_counter.h b/cc/debug/frame_rate_counter.h
new file mode 100644
index 0000000..24d4926
--- /dev/null
+++ b/cc/debug/frame_rate_counter.h
@@ -0,0 +1,57 @@
+// 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.
+
+#ifndef CC_DEBUG_FRAME_RATE_COUNTER_H_
+#define CC_DEBUG_FRAME_RATE_COUNTER_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/time.h"
+#include "cc/debug/ring_buffer.h"
+
+namespace cc {
+
+// This class maintains a history of timestamps, and provides functionality to
+// intelligently compute average frames per second.
+class FrameRateCounter {
+ public:
+  static scoped_ptr<FrameRateCounter> Create(bool has_impl_thread);
+
+  int current_frame_number() const { return ring_buffer_.CurrentIndex(); }
+  int dropped_frame_count() const { return dropped_frame_count_; }
+  size_t time_stamp_history_size() const { return ring_buffer_.BufferSize(); }
+
+  void SaveTimeStamp(base::TimeTicks timestamp);
+
+  // n = 0 returns the oldest frame interval retained in the history, while n =
+  // time_stamp_history_size() - 1 returns the most recent frame interval.
+  base::TimeDelta RecentFrameInterval(size_t n) const;
+
+  // This is a heuristic that can be used to ignore frames in a reasonable way.
+  // Returns true if the given frame interval is too fast or too slow, based on
+  // constant thresholds.
+  bool IsBadFrameInterval(
+      base::TimeDelta interval_between_consecutive_frames) const;
+
+  void GetMinAndMaxFPS(double* min_fps, double* max_fps) const;
+  double GetAverageFPS() const;
+
+  typedef RingBuffer<base::TimeTicks, 136> RingBufferType;
+  RingBufferType::Iterator begin() const { return ring_buffer_.Begin(); }
+  RingBufferType::Iterator end() const { return ring_buffer_.End(); }
+
+ private:
+  explicit FrameRateCounter(bool has_impl_thread);
+
+  RingBufferType ring_buffer_;
+
+  bool has_impl_thread_;
+  int dropped_frame_count_;
+
+  DISALLOW_COPY_AND_ASSIGN(FrameRateCounter);
+};
+
+}  // namespace cc
+
+#endif  // CC_DEBUG_FRAME_RATE_COUNTER_H_