cc: Improve frame/commit accounting

cc/frame_rate_counter.cc

Index: cc/frame_rate_counter.cc
diff --git a/cc/frame_rate_counter.cc b/cc/frame_rate_counter.cc
index a02486bd0ec026e84e0d85f985f0d12ed7f3b15d..9e63977d70a437441d5745a8b50f1d3320c1d667 100644
--- a/cc/frame_rate_counter.cc
+++ b/cc/frame_rate_counter.cc
@@ -13,10 +13,6 @@
 
 namespace cc {
 
-const double CCFrameRateCounter::kFrameTooFast = 1.0 / 70.0; // measured in seconds
-const double CCFrameRateCounter::kFrameTooSlow = 1.0 / 12.0;
-const double CCFrameRateCounter::kDroppedFrameTime = 1.0 / 50.0;
-
 // safeMod works on -1, returning m-1 in that case.
 static inline int safeMod(int number, int modulus)
 {
@@ -28,6 +24,19 @@ scoped_ptr<CCFrameRateCounter> CCFrameRateCounter::create() {
   return make_scoped_ptr(new CCFrameRateCounter());
 }
 
+void CCFrameRateCounter::setTimebaseAndInterval(base::TimeTicks timebase, base::TimeDelta interval)
+{
+    if (interval != m_interval) {
+        base::TimeTicks now = base::TimeTicks::Now();
+        m_vsyncCount = currentVsyncCount(now);
+        m_intervalChangedTime = now;
+        m_interval = interval;
+    }
+
+    m_frameTooFastSeconds = 0.8 * interval.InSecondsF();
+    m_frameTooSlowSeconds = 1.0 / 12.0;
+}
+
 inline base::TimeDelta CCFrameRateCounter::frameInterval(int frameNumber) const
 {
     return m_timeStampHistory[frameIndex(frameNumber)] -
@@ -40,8 +49,10 @@ inline int CCFrameRateCounter::frameIndex(int frameNumber) const
 }
 
 CCFrameRateCounter::CCFrameRateCounter()
-    : m_currentFrameNumber(1)
-    , m_droppedFrameCount(0)
+    : m_frameTooFastSeconds(0)
+    , m_frameTooSlowSeconds(0)
+    , m_vsyncCount(0)
+    , m_currentFrameNumber(1)
 {
     m_timeStampHistory[0] = base::TimeTicks::Now();
     m_timeStampHistory[1] = m_timeStampHistory[0];
@@ -59,9 +70,6 @@ void CCFrameRateCounter::markBeginningOfFrame(base::TimeTicks timestamp)
         WebKit::Platform::current()->histogramCustomCounts("Renderer4.CompositorThreadImplDrawDelay", static_cast<int>(drawDelayMs), 1, 120, 60);
     }
 
-    if (!isBadFrameInterval(frameIntervalSeconds) &&
-        frameIntervalSeconds.InSecondsF() > kDroppedFrameTime)
-        ++m_droppedFrameCount;
 }
 
 void CCFrameRateCounter::markEndOfFrame()
@@ -71,9 +79,10 @@ void CCFrameRateCounter::markEndOfFrame()
 
 bool CCFrameRateCounter::isBadFrameInterval(base::TimeDelta intervalBetweenConsecutiveFrames) const
 {
+    ASSERT(m_interval != base::TimeDelta());
     bool schedulerAllowsDoubleFrames = !CCProxy::hasImplThread();
-    bool intervalTooFast = schedulerAllowsDoubleFrames && intervalBetweenConsecutiveFrames.InSecondsF() < kFrameTooFast;
-    bool intervalTooSlow = intervalBetweenConsecutiveFrames.InSecondsF() > kFrameTooSlow;
+    bool intervalTooFast = schedulerAllowsDoubleFrames && intervalBetweenConsecutiveFrames.InSecondsF() < m_frameTooFastSeconds;
+    bool intervalTooSlow = intervalBetweenConsecutiveFrames.InSecondsF() > m_frameTooSlowSeconds;
     return intervalTooFast || intervalTooSlow;
 }
 
@@ -82,6 +91,14 @@ bool CCFrameRateCounter::isBadFrame(int frameNumber) const
     return isBadFrameInterval(frameInterval(frameNumber));
 }
 
+int64_t CCFrameRateCounter::currentVsyncCount(base::TimeTicks now) const
+{
+    int64_t vsyncCount = m_vsyncCount;
+    if (m_interval != base::TimeDelta())
+        vsyncCount += (now - m_intervalChangedTime + (m_interval/2)) / m_interval;
+    return vsyncCount;
+}
+
 void CCFrameRateCounter::getAverageFPSAndStandardDeviation(double& averageFPS, double& standardDeviation) const
 {
     int frame = m_currentFrameNumber - 1;
@@ -131,5 +148,15 @@ base::TimeTicks CCFrameRateCounter::timeStampOfRecentFrame(int n)
     return m_timeStampHistory[desiredIndex];
 }
 
+void CCFrameRateCounter::renderingStats(CCRenderingStats* stats) const
+{
+    ASSERT(m_interval != base::TimeDelta());
+
+    base::TimeTicks now = base::TimeTicks::Now();
+    stats->vsyncCount = currentVsyncCount(now);
+    stats->rendererFrameCount = m_currentFrameNumber - 1;
+    stats->droppedFrameCount = stats->vsyncCount - stats->rendererFrameCount;
+}
+
 }  // namespace cc