cc: Record statistics about approximated content.

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 94c3d201639d0dd90a29545ba18ca067f43edd8a..d96d2f03263f85eed37bb3c92e6cb6a40ff47fa5 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -238,6 +238,9 @@ void PictureLayerImpl::AppendQuads(QuadSink* quad_sink,
     if (visible_geometry_rect.IsEmpty())
       continue;
 
+    append_quads_data->visible_content_area +=
+        visible_geometry_rect.width() * visible_geometry_rect.height();
+
     if (!*iter || !iter->IsReadyToDraw()) {
       if (draw_checkerboard_for_missing_tiles()) {
         scoped_ptr<CheckerboardDrawQuad> quad = CheckerboardDrawQuad::Create();
@@ -258,6 +261,8 @@ void PictureLayerImpl::AppendQuads(QuadSink* quad_sink,
 
       append_quads_data->num_missing_tiles++;
       append_quads_data->had_incomplete_tile = true;
+      append_quads_data->approximated_visible_content_area +=
+          visible_geometry_rect.width() * visible_geometry_rect.height();
       continue;
     }
 
@@ -323,6 +328,11 @@ void PictureLayerImpl::AppendQuads(QuadSink* quad_sink,
     DCHECK(draw_quad);
     quad_sink->Append(draw_quad.Pass());
 
+    if (iter->priority(ACTIVE_TREE).resolution == LOW_RESOLUTION) {

[enne (OOO), 2014/04/29 17:38:41]

This is not entirely right.  You could be using a non ideal resolution tile of a
scale less than high resolution too.

[ernstm, 2014/04/29 18:40:14]

I changed this to != HIGH_RESOLUTION. That should capture all approximated
cases, right?

[enne (OOO), 2014/04/29 18:46:38]

You can sometimes have a non-ideal resolution that's higher than high resolution
in the case of a zoom in.  I'd call that not approximated, but it's up to you.

[ernstm, 2014/04/29 19:00:12]

I assume we need to resample/interpolate in that case, which can result in
artifacts. It's not really an approximation, but it is different than the ideal
result.

+      append_quads_data->approximated_visible_content_area +=
+          visible_geometry_rect.width() * visible_geometry_rect.height();
+    }
+
     if (seen_tilings.empty() || seen_tilings.back() != iter.CurrentTiling())
       seen_tilings.push_back(iter.CurrentTiling());
   }