cc: Use commit to activation time in repaint HUD

In an effort to remove rasterize_time from the impl stats, I'm using
commit_to_activate_duration in its place, which should give a better
indication of the commit to activation time (raster + management time).

BUG=

Review URL: https://codereview.chromium.org/689503002

Cr-Commit-Position: refs/heads/master@{#302633}

cc/debug/paint_time_counter.cc

@@ -11,18 +11,11 @@ scoped_ptr<PaintTimeCounter> PaintTimeCounter::Create() {
   return make_scoped_ptr(new PaintTimeCounter());
 }
 
-PaintTimeCounter::PaintTimeCounter()
-  : can_save_paint_time_delta_(false) {
+PaintTimeCounter::PaintTimeCounter() {
 }
 
-void PaintTimeCounter::SavePaintTime(const base::TimeDelta& total_paint_time) {
-  if (can_save_paint_time_delta_) {
-    base::TimeDelta paint_time = total_paint_time - last_total_paint_time_;
+void PaintTimeCounter::SavePaintTime(const base::TimeDelta& paint_time) {
   ring_buffer_.SaveToBuffer(paint_time);
-  }
-
-  last_total_paint_time_ = total_paint_time;
-  can_save_paint_time_delta_ = true;
 }
 
 void PaintTimeCounter::GetMinAndMaxPaintTime(base::TimeDelta* min,
@@ -45,7 +38,6 @@ void PaintTimeCounter::GetMinAndMaxPaintTime(base::TimeDelta* min,
 
 void PaintTimeCounter::ClearHistory() {
   ring_buffer_.Clear();
-  can_save_paint_time_delta_ = false;
 }
 
 }  // namespace cc

cc/debug/paint_time_counter.h

@@ -36,8 +36,6 @@ class PaintTimeCounter {
   PaintTimeCounter();
 
   RingBufferType ring_buffer_;
-  base::TimeDelta last_total_paint_time_;
-  bool can_save_paint_time_delta_;
 
   DISALLOW_COPY_AND_ASSIGN(PaintTimeCounter);
 };

cc/debug/rendering_stats.cc

@@ -28,6 +28,10 @@ void RenderingStats::TimeDeltaList::Add(const TimeDeltaList& other) {
   values.insert(values.end(), other.values.begin(), other.values.end());
 }
 
+base::TimeDelta RenderingStats::TimeDeltaList::GetLastTimeDelta() const {
+  return values.empty() ? base::TimeDelta() : values.back();
+}
+
 RenderingStats::MainThreadRenderingStats::MainThreadRenderingStats()
     : painted_pixel_count(0), recorded_pixel_count(0) {
 }

cc/debug/rendering_stats.h

@@ -28,6 +28,8 @@ struct CC_EXPORT RenderingStats {
 
     void Add(const TimeDeltaList& other);
 
+    base::TimeDelta GetLastTimeDelta() const;
+
    private:
     std::list<base::TimeDelta> values;
   };

cc/layers/heads_up_display_layer_impl.cc

@@ -565,13 +565,8 @@ SkRect HeadsUpDisplayLayerImpl::DrawPaintTimeDisplay(
       "%.1f-%.1f", paint_time_graph_.min, paint_time_graph_.max);
 
   paint.setColor(DebugColors::PaintTimeDisplayTextAndGraphColor());
-  DrawText(canvas,
-           &paint,
-           "Page paint time (ms)",
-           SkPaint::kLeft_Align,
-           kFontHeight,
-           text_bounds.left(),
-           text_bounds.bottom());
+  DrawText(canvas, &paint, "Compositor frame time (ms)", SkPaint::kLeft_Align,
+           kFontHeight, text_bounds.left(), text_bounds.bottom());
   DrawText(canvas,
            &paint,
            value_text,

cc/trees/layer_tree_host_impl.cc

@@ -1874,9 +1874,11 @@ void LayerTreeHostImpl::ActivateSyncTree() {
   if (debug_state_.continuous_painting) {
     const RenderingStats& stats =
         rendering_stats_instrumentation_->GetRenderingStats();
-    paint_time_counter_->SavePaintTime(stats.main_stats.paint_time +
-                                       stats.main_stats.record_time +
-                                       stats.impl_stats.rasterize_time);
+    // TODO(hendrikw): This requires a different metric when we commit directly
+    // to the active tree.  See crbug.com/429311.
+    paint_time_counter_->SavePaintTime(
+        stats.impl_stats.commit_to_activate_duration.GetLastTimeDelta() +
+        stats.impl_stats.draw_duration.GetLastTimeDelta());
   }
 
   if (time_source_client_adapter_ && time_source_client_adapter_->Active())