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

cc/resources/picture_layer_tiling.cc

Index: cc/resources/picture_layer_tiling.cc
diff --git a/cc/resources/picture_layer_tiling.cc b/cc/resources/picture_layer_tiling.cc
index 862d4d8b46750864ef453049b26d21ad7fb193d5..359459df90f1af647da8e72eee93bfb6ea8a0cfe 100644
--- a/cc/resources/picture_layer_tiling.cc
+++ b/cc/resources/picture_layer_tiling.cc
@@ -79,8 +79,7 @@ void PictureLayerTiling::CreateTile(int i, int j) {
   TileMapKey key(i, j);
   DCHECK(tiles_.find(key) == tiles_.end());
 
-  gfx::Rect paint_rect = tiling_data_.TileBoundsWithBorder(i, j);
-  gfx::Rect tile_rect = paint_rect;
+  gfx::Rect tile_rect = tiling_data_.TileBoundsWithBorder(i, j);
   tile_rect.set_size(tiling_data_.max_texture_size());
 
   // Check our twin for a valid tile.
@@ -90,7 +89,7 @@ void PictureLayerTiling::CreateTile(int i, int j) {
     Tile* candidate_tile = twin->TileAt(i, j);
     if (candidate_tile) {
       gfx::Rect rect =
-          gfx::ToEnclosingRect(ScaleRect(paint_rect, 1.0f / contents_scale_));
+          gfx::ToEnclosingRect(ScaleRect(tile_rect, 1.0f / contents_scale_));
       if (!client_->GetInvalidation()->Intersects(rect)) {
         tiles_[key] = candidate_tile;
         return;
@@ -295,10 +294,15 @@ void PictureLayerTiling::UpdateTilePriorities(
     double current_frame_time_in_seconds,
     bool store_screen_space_quads_on_tiles,
     size_t max_tiles_for_interest_area) {
-  if (ContentRect().IsEmpty())
+  if (!NeedsUpdateForFrameAtTime(current_frame_time_in_seconds)) {
+    // This should never be zero for the purposes of has_ever_been_updated().
+    DCHECK_NE(current_frame_time_in_seconds, 0.0);
     return;
-  if (!NeedsUpdateForFrameAtTime(current_frame_time_in_seconds))
+  }
+  if (ContentRect().IsEmpty()) {
+    last_impl_frame_time_in_seconds_ = current_frame_time_in_seconds;
     return;
+  }
 
   gfx::Rect viewport_in_content_space =
       gfx::ToEnclosingRect(gfx::ScaleRect(viewport_in_layer_space,