cc: Fix impl-side painting flashing due to missing tiles

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 24a83cb20d429bcac34b931df3ad32368278a5cd..ea97208f6516e1d7d94e5cdfb304e998d370efec 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -377,8 +377,9 @@ skia::RefPtr<SkPicture> PictureLayerImpl::GetPicture() {
   return pile_->GetFlattenedPicture();
 }
 
-scoped_refptr<Tile> PictureLayerImpl::CreateTile(PictureLayerTiling* tiling,
-                                                 gfx::Rect content_rect) {
+scoped_refptr<Tile> PictureLayerImpl::CreateTile(
+    const PictureLayerTiling* tiling,

[enne (OOO), 2013/05/02 23:25:37]

This isn't actually needed.  I previously was trying to CreateTile as my check
to see if a null tile was ok, but abandoned that due to the fact that a null
tile can be both missing recorded region or live tiles rect.  The right check is
just to make sure the tiling has been updated.

However, making this const seemed pretty reasonable, so I left it.

+    gfx::Rect content_rect) {
   if (!pile_->CanRaster(tiling->contents_scale(), content_rect))
     return scoped_refptr<Tile>();
 
@@ -524,6 +525,13 @@ void PictureLayerImpl::SyncTiling(
   if (!DrawsContent() || tiling->contents_scale() < MinimumContentsScale())
     return;
   tilings_->Clone(tiling);
+
+  // If this tree needs update draw properties, then the tiling will
+  // get updated prior to drawing or activation.  If this tree does not
+  // need update draw properties, then its transforms are up to date and
+  // we can create tiles for this tiling immediately.
+  if (!layer_tree_impl()->needs_update_draw_properties())
+    UpdateTilePriorities();
 }
 
 void PictureLayerImpl::SetIsMask(bool is_mask) {
@@ -557,6 +565,7 @@ ResourceProvider::ResourceId PictureLayerImpl::ContentsResourceId() const {
 
 bool PictureLayerImpl::AreVisibleResourcesReady() const {
   DCHECK(layer_tree_impl()->IsPendingTree());
+  DCHECK(!layer_tree_impl()->needs_update_draw_properties());
   DCHECK(ideal_contents_scale_);
 
   if (!tilings_->num_tilings())
@@ -588,6 +597,7 @@ bool PictureLayerImpl::AreVisibleResourcesReady() const {
   Region missing_region = rect;
   for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
     PictureLayerTiling* tiling = tilings_->tiling_at(i);
+    DCHECK(tiling->has_ever_been_updated());
 
     if (tiling->contents_scale() < min_acceptable_scale)
       continue;