Add fixed raster scale use counter histograms.

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 b2b8def1ad4ca91430fab762063e48576df5c398..0605c7e17326a159acc4ccee7acf0240824c7616 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -69,6 +69,7 @@ PictureLayerImpl::PictureLayerImpl(LayerTreeImpl* tree_impl,
       ideal_device_scale_(0.f),
       ideal_source_scale_(0.f),
       ideal_contents_scale_(0.f),
+      last_ideal_source_scale_(0.f),
       raster_page_scale_(0.f),
       raster_device_scale_(0.f),
       raster_source_scale_(0.f),
@@ -433,6 +434,21 @@ bool PictureLayerImpl::UpdateTiles() {
     AddTilingsForRasterScale();
   }
 
+  // Inform layer tree impl if we will have blurry content because of fixed
+  // raster scale (note that this check should happen after we
+  // ReclaculateRasterScales, since that's the function that will determine
+  // whether our raster scale is fixed.
+  if (raster_source_scale_is_fixed_ && !has_will_change_transform_hint()) {
+    if (std::abs(raster_source_scale_ - ideal_source_scale_) >=
+        std::numeric_limits<float>::epsilon()) {

[danakj, 2016/05/13 20:41:47]

Why?

[vmpstr, 2016/05/13 21:17:10]

Acknowledged.

+      layer_tree_impl()->SetFixedRasterScaleHasBlurryContent();
+    }
+    if (std::abs(ideal_source_scale_ - last_ideal_source_scale_) >=
+        std::numeric_limits<float>::epsilon()) {
+      layer_tree_impl()->SetFixedRasterScaleAttemptedToChangeScale();
+    }
+  }
+
   if (layer_tree_impl()->IsActiveTree())
     AddLowResolutionTilingIfNeeded();
 
@@ -1206,6 +1222,7 @@ void PictureLayerImpl::UpdateIdealScales() {
                           : 1.f;
   ideal_device_scale_ = layer_tree_impl()->device_scale_factor();
   ideal_contents_scale_ = std::max(GetIdealContentsScale(), min_contents_scale);
+  last_ideal_source_scale_ = ideal_source_scale_;
   ideal_source_scale_ =
       ideal_contents_scale_ / ideal_page_scale_ / ideal_device_scale_;
 }