Update from https://crrev.com/309415

cc/test/fake_picture_layer_tiling_client.cc

Index: cc/test/fake_picture_layer_tiling_client.cc
diff --git a/cc/test/fake_picture_layer_tiling_client.cc b/cc/test/fake_picture_layer_tiling_client.cc
index 6c1dc98de0e6f91420fc523877f6f66327a49ff4..293d4f6563e82ad1cf0fe684fa7fdc55bce5bb06 100644
--- a/cc/test/fake_picture_layer_tiling_client.cc
+++ b/cc/test/fake_picture_layer_tiling_client.cc
@@ -14,9 +14,9 @@ namespace cc {
 FakePictureLayerTilingClient::FakePictureLayerTilingClient()
     : tile_manager_(new FakeTileManager(&tile_manager_client_)),
       pile_(FakePicturePileImpl::CreateInfiniteFilledPile()),
-      twin_tiling_(NULL),
-      recycled_twin_tiling_(NULL),
-      allow_create_tile_(true),
+      twin_set_(nullptr),
+      twin_tiling_(nullptr),
+      recycled_twin_tiling_(nullptr),
       max_tile_priority_bin_(TilePriority::NOW) {
 }
 
@@ -27,9 +27,9 @@ FakePictureLayerTilingClient::FakePictureLayerTilingClient(
       tile_manager_(
           new FakeTileManager(&tile_manager_client_, resource_pool_.get())),
       pile_(FakePicturePileImpl::CreateInfiniteFilledPile()),
-      twin_tiling_(NULL),
-      recycled_twin_tiling_(NULL),
-      allow_create_tile_(true),
+      twin_set_(nullptr),
+      twin_tiling_(nullptr),
+      recycled_twin_tiling_(nullptr),
       max_tile_priority_bin_(TilePriority::NOW) {
 }
 
@@ -37,10 +37,8 @@ FakePictureLayerTilingClient::~FakePictureLayerTilingClient() {
 }
 
 scoped_refptr<Tile> FakePictureLayerTilingClient::CreateTile(
-    PictureLayerTiling*,
+    float content_scale,
     const gfx::Rect& rect) {
-  if (!allow_create_tile_)
-    return scoped_refptr<Tile>();
   return tile_manager_->CreateTile(pile_.get(), tile_size_, rect, 1, 0, 0, 0);
 }
 
@@ -65,7 +63,13 @@ const Region* FakePictureLayerTilingClient::GetPendingInvalidation() {
 const PictureLayerTiling*
 FakePictureLayerTilingClient::GetPendingOrActiveTwinTiling(
     const PictureLayerTiling* tiling) const {
-  return twin_tiling_;
+  if (!twin_set_)
+    return twin_tiling_;
+  for (size_t i = 0; i < twin_set_->num_tilings(); ++i) {
+    if (twin_set_->tiling_at(i)->contents_scale() == tiling->contents_scale())
+      return twin_set_->tiling_at(i);
+  }
+  return nullptr;
 }
 
 PictureLayerTiling* FakePictureLayerTilingClient::GetRecycledTwinTiling(