cc: Record statistics about approximated content.

cc/debug/rendering_stats.cc

Index: cc/debug/rendering_stats.cc
diff --git a/cc/debug/rendering_stats.cc b/cc/debug/rendering_stats.cc
index 5c194c6256f3781b1b4c6241f1102cef7d85312d..3e123b667c774656f88f421225e5f1963ad64f69 100644
--- a/cc/debug/rendering_stats.cc
+++ b/cc/debug/rendering_stats.cc
@@ -33,7 +33,10 @@ void MainThreadRenderingStats::Add(const MainThreadRenderingStats& other) {
 
 ImplThreadRenderingStats::ImplThreadRenderingStats()
     : frame_count(0),
-      rasterized_pixel_count(0) {}
+      rasterized_pixel_count(0),
+      visible_content_area(0),
+      approximated_visible_content_area(0) {
+}
 
 scoped_refptr<base::debug::ConvertableToTraceFormat>
 ImplThreadRenderingStats::AsTraceableData() const {
@@ -41,6 +44,9 @@ ImplThreadRenderingStats::AsTraceableData() const {
   record_data->SetInteger("frame_count", frame_count);
   record_data->SetDouble("rasterize_time", rasterize_time.InSecondsF());
   record_data->SetInteger("rasterized_pixel_count", rasterized_pixel_count);
+  record_data->SetInteger("visible_content_area", visible_content_area);
+  record_data->SetInteger("approximated_visible_content_area",
+                          approximated_visible_content_area);
   return TracedValue::FromValue(record_data.release());
 }
 
@@ -49,6 +55,8 @@ void ImplThreadRenderingStats::Add(const ImplThreadRenderingStats& other) {
   rasterize_time += other.rasterize_time;
   analysis_time += other.analysis_time;
   rasterized_pixel_count += other.rasterized_pixel_count;
+  visible_content_area += other.visible_content_area;
+  approximated_visible_content_area += other.approximated_visible_content_area;
 }
 
 void RenderingStats::Add(const RenderingStats& other) {