cc: add RingBuffer class for timestamp storing in FrameRateCounter

cc/heads_up_display_layer_impl.cc

Index: cc/heads_up_display_layer_impl.cc
diff --git a/cc/heads_up_display_layer_impl.cc b/cc/heads_up_display_layer_impl.cc
index 177f349558981a9a7d302b80ad99d555fb2c584b..e65015462937cb1bd5000d85c7179bb2cdecc682 100644
--- a/cc/heads_up_display_layer_impl.cc
+++ b/cc/heads_up_display_layer_impl.cc
@@ -208,9 +208,10 @@ int HeadsUpDisplayLayerImpl::drawFPSCounter(SkCanvas* canvas, FrameRateCounter*
 void HeadsUpDisplayLayerImpl::drawFPSCounterText(SkCanvas* canvas, SkPaint& paint, FrameRateCounter* fpsCounter, SkRect bounds)
 {
     // Update FPS text - not every frame so text is readable
-    if (base::TimeDelta(fpsCounter->timeStampOfRecentFrame(0) - textUpdateTime).InSecondsF() > 0.25) {
+    base::TimeTicks now = base::TimeTicks::Now();

[egraether, 2013/01/10 02:32:09]

This should just use the current timestamp, which is easier to understand.

+    if (base::TimeDelta(now - textUpdateTime).InSecondsF() > 0.25) {
         m_averageFPS = fpsCounter->getAverageFPS();
-        textUpdateTime = fpsCounter->timeStampOfRecentFrame(0);
+        textUpdateTime = now;
     }
 
     // Draw FPS text.