Limit image filtering during scale animations

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 cf2e36a209bdcb576c5ca138e6673b97955ed079..f8c726ebb8774863294953e611c24579d7a64f02 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -74,6 +74,7 @@ PictureLayerImpl::PictureLayerImpl(LayerTreeImpl* tree_impl,
       raster_source_scale_(0.f),
       raster_contents_scale_(0.f),
       low_res_raster_contents_scale_(0.f),
+      source_scale_has_changed_(false),
       was_screen_space_transform_animating_(false),
       only_used_low_res_last_append_quads_(false),
       is_mask_(is_mask),
@@ -545,6 +546,10 @@ void PictureLayerImpl::UpdateRasterSource(
   if (!pending_set) {
     raster_source_->SetImageDecodeController(
         layer_tree_impl()->image_decode_controller());
+    raster_source_->SetImageScalingOptimization(
+        source_scale_has_changed_
+            ? DisplayListRasterSource::ImageScalingOptimization::Animation
+            : DisplayListRasterSource::ImageScalingOptimization::Static);
   }
 
   // The |new_invalidation| must be cleared before updating tilings since they
@@ -946,12 +951,23 @@ void PictureLayerImpl::AddLowResolutionTilingIfNeeded() {
 void PictureLayerImpl::RecalculateRasterScales() {
   const float old_raster_contents_scale = raster_contents_scale_;
   const float old_raster_page_scale = raster_page_scale_;
+  const float old_raster_source_scale = raster_source_scale_;
 
   raster_device_scale_ = ideal_device_scale_;
   raster_page_scale_ = ideal_page_scale_;
   raster_source_scale_ = ideal_source_scale_;
   raster_contents_scale_ = ideal_contents_scale_;
 
+  // If we're not animating, or leaving an animation, and the
+  // ideal_source_scale_ changes, then things are unpredictable, and we
+  // may need to tweak some source rasterization params.
+  // TODO(fmalita): this should be generalized for screen transform changes.
+  if (old_raster_source_scale &&
+      !draw_properties().screen_space_transform_is_animating &&
+      !was_screen_space_transform_animating_ &&
+      old_raster_source_scale != ideal_source_scale_)
+    source_scale_has_changed_ = true;
+
   // During pinch we completely ignore the current ideal scale, and just use
   // a multiple of the previous scale.
   bool is_pinching = layer_tree_impl()->PinchGestureActive();
@@ -1122,6 +1138,7 @@ void PictureLayerImpl::ResetRasterScale() {
   raster_source_scale_ = 0.f;
   raster_contents_scale_ = 0.f;
   low_res_raster_contents_scale_ = 0.f;
+  source_scale_has_changed_ = false;
 }
 
 bool PictureLayerImpl::CanHaveTilings() const {
@@ -1207,6 +1224,7 @@ void PictureLayerImpl::AsValueInto(
   state->SetDouble("ideal_contents_scale", ideal_contents_scale_);
   state->SetDouble("raster_contents_scale", raster_contents_scale_);
   state->SetDouble("geometry_contents_scale", MaximumTilingContentsScale());
+  state->SetBoolean("source_scale_changed", source_scale_has_changed_);
   state->BeginArray("tilings");
   tilings_->AsValueInto(state);
   state->EndArray();