cc: RemoveAllTilings on tile size change

- Update the tilings if either the layer size or the tile size
  changes.
- Added a unit test to make sure we correctly resize tiles when
  the tilesize changes

BUG=400864

Review URL: https://codereview.chromium.org/719123002

Cr-Commit-Position: refs/heads/master@{#303882}

2 files changed, 27 insertions, 5 deletions

diff --git a/cc/resources/picture_layer_tiling.cc b/cc/resources/picture_layer_tiling.cc
index 562b111..04b18c3 100644
--- a/cc/resources/picture_layer_tiling.cc
+++ b/cc/resources/picture_layer_tiling.cc
@@ -172,13 +172,11 @@ void PictureLayerTiling::UpdateTilesToCurrentRasterSource(
     const gfx::Size& new_layer_bounds) {
   DCHECK(!new_layer_bounds.IsEmpty());
 
-  gfx::Size tile_size = tiling_data_.max_texture_size();
+  gfx::Size content_bounds =
+      gfx::ToCeiledSize(gfx::ScaleSize(new_layer_bounds, contents_scale_));
+  gfx::Size tile_size = client_->CalculateTileSize(content_bounds);
 
   if (new_layer_bounds != layer_bounds_) {
-    gfx::Size content_bounds =
-        gfx::ToCeiledSize(gfx::ScaleSize(new_layer_bounds, contents_scale_));
-
-    tile_size = client_->CalculateTileSize(content_bounds);
     if (tile_size.IsEmpty()) {
       layer_bounds_ = gfx::Size();
       content_bounds = gfx::Size();
diff --git a/cc/resources/picture_layer_tiling_unittest.cc b/cc/resources/picture_layer_tiling_unittest.cc
index 675ce88..786f943 100644
--- a/cc/resources/picture_layer_tiling_unittest.cc
+++ b/cc/resources/picture_layer_tiling_unittest.cc
@@ -2178,5 +2178,29 @@ TEST(PictureLayerTilingTest, RecycledTilesClearedOnReset) {
   EXPECT_FALSE(recycle_tiling->TileAt(0, 0));
 }
 
+TEST_F(PictureLayerTilingIteratorTest, ResizeTilesAndUpdateToCurrent) {
+  // The tiling has four rows and three columns.
+  Initialize(gfx::Size(150, 100), 1, gfx::Size(250, 150));
+  tiling_->CreateAllTilesForTesting();
+  EXPECT_EQ(150, tiling_->TilingDataForTesting().max_texture_size().width());
+  EXPECT_EQ(100, tiling_->TilingDataForTesting().max_texture_size().height());
+  EXPECT_EQ(4u, tiling_->AllRefTilesForTesting().size());
+
+  client_.SetTileSize(gfx::Size(250, 200));
+  client_.set_tree(PENDING_TREE);
+
+  // Tile size in the tiling should still be 150x100.
+  EXPECT_EQ(150, tiling_->TilingDataForTesting().max_texture_size().width());
+  EXPECT_EQ(100, tiling_->TilingDataForTesting().max_texture_size().height());
+
+  Region invalidation;
+  tiling_->UpdateTilesToCurrentRasterSource(invalidation, gfx::Size(250, 150));
+
+  // Tile size in the tiling should be resized to 250x200.
+  EXPECT_EQ(250, tiling_->TilingDataForTesting().max_texture_size().width());
+  EXPECT_EQ(200, tiling_->TilingDataForTesting().max_texture_size().height());
+  EXPECT_EQ(0u, tiling_->AllRefTilesForTesting().size());
+}
+
 }  // namespace
 }  // namespace cc