Raster PictureLayerTiling with fractional translation

cc/tiles/picture_layer_tiling_set.cc

Index: cc/tiles/picture_layer_tiling_set.cc
diff --git a/cc/tiles/picture_layer_tiling_set.cc b/cc/tiles/picture_layer_tiling_set.cc
index 469080f8d85cee8faab7c48b4f5f130936744453..f2762034bb04e78a1a7a2d5b7e7c10cfdc0740ac 100644
--- a/cc/tiles/picture_layer_tiling_set.cc
+++ b/cc/tiles/picture_layer_tiling_set.cc
@@ -81,10 +81,13 @@ void PictureLayerTilingSet::CopyTilingsAndPropertiesFromPendingTwin(
   bool tiling_sort_required = false;
   for (const auto& pending_twin_tiling : pending_twin_set->tilings_) {
     float contents_scale = pending_twin_tiling->contents_scale();
+    gfx::Vector2dF contents_translation =
+        pending_twin_tiling->contents_translation();
     PictureLayerTiling* this_tiling = FindTilingWithScale(contents_scale);

[enne (OOO), 2016/08/22 22:57:39]

What if there are multiple tilings with the same scale but different
translations?

[trchen, 2016/08/29 10:14:48]

Currently the easiest thing to do is to replace. It shouldn't be terribly
difficult to extend the tiling set to accommodate both. I think we can do it in
a separate CL.

     if (!this_tiling) {
-      std::unique_ptr<PictureLayerTiling> new_tiling(new PictureLayerTiling(
-          tree_, contents_scale, raster_source_, client_));
+      std::unique_ptr<PictureLayerTiling> new_tiling(
+          new PictureLayerTiling(tree_, contents_scale, contents_translation,
+                                 raster_source_, client_));
       tilings_.push_back(std::move(new_tiling));
       this_tiling = tilings_.back().get();
       tiling_sort_required = true;
@@ -262,6 +265,7 @@ void PictureLayerTilingSet::MarkAllTilingsNonIdeal() {
 
 PictureLayerTiling* PictureLayerTilingSet::AddTiling(
     float contents_scale,
+    const gfx::Vector2dF& contents_translation,
     scoped_refptr<RasterSource> raster_source) {
   if (!raster_source_)
     raster_source_ = raster_source;
@@ -271,8 +275,8 @@ PictureLayerTiling* PictureLayerTilingSet::AddTiling(
     DCHECK_EQ(tilings_[i]->raster_source(), raster_source.get());
   }
 
-  tilings_.push_back(base::WrapUnique(
-      new PictureLayerTiling(tree_, contents_scale, raster_source, client_)));
+  tilings_.push_back(base::WrapUnique(new PictureLayerTiling(
+      tree_, contents_scale, contents_translation, raster_source, client_)));
   PictureLayerTiling* appended = tilings_.back().get();
   state_since_last_tile_priority_update_.added_tilings = true;