Re-raster during scale animations for GPU-rasterized layers without text

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 ede7da0ac3a5853216a7103b38852af889669b7e..98da42dac3a1c1adfcba5c27ff6c44cac73d88d9 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -1023,6 +1023,11 @@ bool PictureLayerImpl::ShouldAdjustRasterScale() const {
       draw_properties().screen_space_transform_is_animating)
     return true;
 
+  if (draw_properties().screen_space_transform_is_animating &&
+      raster_contents_scale_ != ideal_contents_scale_ &&
+      ShouldAdjustRasterScaleDuringScaleAnimations())
+    return true;
+
   bool is_pinching = layer_tree_impl()->PinchGestureActive();
   if (is_pinching && raster_page_scale_) {
     // We change our raster scale when it is:
@@ -1117,11 +1122,12 @@ void PictureLayerImpl::RecalculateRasterScales() {
   raster_contents_scale_ =
       std::max(raster_contents_scale_, MinimumContentsScale());
 
-  // Since we're not re-rasterizing during animation, rasterize at the maximum
+  // If we're not re-rasterizing during animation, rasterize at the maximum
   // scale that will occur during the animation, if the maximum scale is
   // known. However, to avoid excessive memory use, don't rasterize at a scale
   // at which this layer would become larger than the viewport.
-  if (draw_properties().screen_space_transform_is_animating) {
+  if (draw_properties().screen_space_transform_is_animating &&
+      !ShouldAdjustRasterScaleDuringScaleAnimations()) {
     bool can_raster_at_maximum_scale = false;
     if (draw_properties().maximum_animation_contents_scale > 0.f) {
       gfx::Size bounds_at_maximum_scale = gfx::ToCeiledSize(gfx::ScaleSize(
@@ -1299,6 +1305,15 @@ void PictureLayerImpl::SanityCheckTilingState() const {
 #endif
 }
 
+bool PictureLayerImpl::ShouldAdjustRasterScaleDuringScaleAnimations() const {
+  if (!layer_tree_impl()->use_gpu_rasterization())
+    return false;
+  if (pile_->has_text())

[enne (OOO), 2014/08/20 18:15:49]

Can you add some comments about why this is needed? As far as I know, this is a
performance workaround for the fact that Ganesh is slow to reraster text at
different scales.  Is there a bug that can be linked to?

[ajuma, 2014/08/20 18:51:29]

Done.

+    return false;
+
+  return true;
+}
+
 float PictureLayerImpl::MaximumTilingContentsScale() const {
   float max_contents_scale = MinimumContentsScale();
   for (size_t i = 0; i < tilings_->num_tilings(); ++i) {