Initial import attempt, just to play with. Many things disabled/removed

ui/cc/cc/CCFrameRateCounter.h

Index: ui/cc/cc/CCFrameRateCounter.h
diff --git a/ui/cc/cc/CCFrameRateCounter.h b/ui/cc/cc/CCFrameRateCounter.h
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+++ b/ui/cc/cc/CCFrameRateCounter.h
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+/*
+ * Copyright (C) 2012 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1.  Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ * 2.  Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef CCFrameRateCounter_h
+#define CCFrameRateCounter_h
+
+#if USE(ACCELERATED_COMPOSITING)
+
+#include <wtf/Noncopyable.h>
+#include <wtf/PassOwnPtr.h>
+
+namespace WebCore {
+
+// This class maintains a history of timestamps, and provides functionality to
+// intelligently compute average frames per second (and standard deviation).
+class CCFrameRateCounter {
+    WTF_MAKE_NONCOPYABLE(CCFrameRateCounter);
+public:
+    static PassOwnPtr<CCFrameRateCounter> create()
+    {
+        return adoptPtr(new CCFrameRateCounter());
+    }
+
+    void markBeginningOfFrame(double timestamp);
+    void markEndOfFrame();
+    int currentFrameNumber() const { return m_currentFrameNumber; }
+    void getAverageFPSAndStandardDeviation(double& averageFPS, double& standardDeviation) const;
+    int timeStampHistorySize() const { return kTimeStampHistorySize; }
+
+    // n = 0 returns the oldest frame retained in the history,
+    // while n = timeStampHistorySize() - 1 returns the timestamp most recent frame.
+    double timeStampOfRecentFrame(int /* n */);
+
+    // 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(double intervalBetweenConsecutiveFrames) const;
+
+private:
+    CCFrameRateCounter();
+
+    int frameIndex(int frameNumber) const;
+    bool isBadFrame(int frameNumber) const;
+
+    // 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;
+    static const double kFrameTooSlow;
+
+    static const int kTimeStampHistorySize = 120;
+
+    int m_currentFrameNumber;
+    double m_timeStampHistory[kTimeStampHistorySize];
+};
+
+} // namespace WebCore
+
+#endif // USE(ACCELERATED_COMPOSITING)
+
+#endif