CC: Decouple tile-grid-size from tile-size.

Using the tile-size for the tile-grid-size isn't effective, since
these have different scales etc.

This patch adds a new setting such that we can start to tune this
independantly of other settings.

BUG=365877

Review URL: https://codereview.chromium.org/666573002

Cr-Commit-Position: refs/heads/master@{#300420}

cc/layers/picture_layer.cc

@@ -60,7 +60,7 @@ void PictureLayer::SetLayerTreeHost(LayerTreeHost* host) {
   Layer::SetLayerTreeHost(host);
   if (host) {
     pile_->SetMinContentsScale(host->settings().minimum_contents_scale);
-    pile_->SetTileGridSize(host->settings().default_tile_size);
+    pile_->SetTileGridSize(host->settings().default_tile_grid_size);
     pile_->set_slow_down_raster_scale_factor(
         host->debug_state().slow_down_raster_scale_factor);
     pile_->set_show_debug_picture_borders(

cc/layers/picture_layer_unittest.cc

@@ -84,5 +84,23 @@ TEST(PictureLayerTest, SuitableForGpuRasterization) {
   EXPECT_FALSE(layer->IsSuitableForGpuRasterization());
 }
 
+TEST(PictureLayerTest, UseTileGridSize) {
+  LayerTreeSettings settings;
+  settings.default_tile_grid_size = gfx::Size(123, 123);
+
+  MockContentLayerClient client;
+  scoped_refptr<PictureLayer> layer = PictureLayer::Create(&client);
+  FakeLayerTreeHostClient host_client(FakeLayerTreeHostClient::DIRECT_3D);
+  scoped_ptr<FakeLayerTreeHost> host =
+      FakeLayerTreeHost::Create(&host_client, settings);
+  host->SetRootLayer(layer);
+
+  // Tile-grid is set according to its setting.
+  SkTileGridFactory::TileGridInfo info =
+      layer->GetPicturePileForTesting()->GetTileGridInfoForTesting();
+  EXPECT_EQ(info.fTileInterval.width(), 123 - 2 * info.fMargin.width());
+  EXPECT_EQ(info.fTileInterval.height(), 123 - 2 * info.fMargin.height());
+}
+
 }  // namespace
 }  // namespace cc

cc/resources/picture_pile_base.h

@@ -65,6 +65,10 @@ class CC_EXPORT PicturePileBase : public base::RefCounted<PicturePileBase> {
 
   void AsValueInto(base::debug::TracedValue* array) const;
 
+  SkTileGridFactory::TileGridInfo GetTileGridInfoForTesting() const {
+    return tile_grid_info_;
+  }
+
  protected:
   class CC_EXPORT PictureInfo {
    public:

cc/test/fake_picture_pile_impl.cc

@@ -22,7 +22,7 @@ scoped_refptr<FakePicturePileImpl> FakePicturePileImpl::CreateFilledPile(
   scoped_refptr<FakePicturePileImpl> pile(new FakePicturePileImpl());
   pile->tiling().SetTilingSize(layer_bounds);
   pile->tiling().SetMaxTextureSize(tile_size);
-  pile->SetTileGridSize(ImplSidePaintingSettings().default_tile_size);
+  pile->SetTileGridSize(ImplSidePaintingSettings().default_tile_grid_size);
   pile->recorded_viewport_ = gfx::Rect(layer_bounds);
   pile->has_any_recordings_ = true;
   for (int x = 0; x < pile->tiling().num_tiles_x(); ++x) {
@@ -38,7 +38,7 @@ scoped_refptr<FakePicturePileImpl> FakePicturePileImpl::CreateEmptyPile(
   scoped_refptr<FakePicturePileImpl> pile(new FakePicturePileImpl());
   pile->tiling().SetTilingSize(layer_bounds);
   pile->tiling().SetMaxTextureSize(tile_size);
-  pile->SetTileGridSize(ImplSidePaintingSettings().default_tile_size);
+  pile->SetTileGridSize(ImplSidePaintingSettings().default_tile_grid_size);
   pile->recorded_viewport_ = gfx::Rect();
   pile->has_any_recordings_ = false;
   return pile;
@@ -51,7 +51,7 @@ FakePicturePileImpl::CreateEmptyPileThatThinksItHasRecordings(
   scoped_refptr<FakePicturePileImpl> pile(new FakePicturePileImpl());
   pile->tiling().SetTilingSize(layer_bounds);
   pile->tiling().SetMaxTextureSize(tile_size);
-  pile->SetTileGridSize(ImplSidePaintingSettings().default_tile_size);
+  pile->SetTileGridSize(ImplSidePaintingSettings().default_tile_grid_size);
   // This simulates a false positive for this flag.
   pile->recorded_viewport_ = gfx::Rect();
   pile->has_any_recordings_ = true;

cc/trees/layer_tree_settings.cc

@@ -49,6 +49,7 @@ LayerTreeSettings::LayerTreeSettings()
       max_partial_texture_updates(std::numeric_limits<size_t>::max()),
       default_tile_size(gfx::Size(256, 256)),
       max_untiled_layer_size(gfx::Size(512, 512)),
+      default_tile_grid_size(gfx::Size(256, 256)),
       minimum_occlusion_tracking_size(gfx::Size(160, 160)),
       use_pinch_zoom_scrollbars(false),
       use_pinch_virtual_viewport(false),

cc/trees/layer_tree_settings.h

@@ -60,6 +60,7 @@ class CC_EXPORT LayerTreeSettings {
   size_t max_partial_texture_updates;
   gfx::Size default_tile_size;
   gfx::Size max_untiled_layer_size;
+  gfx::Size default_tile_grid_size;
   gfx::Size minimum_occlusion_tracking_size;
   bool use_pinch_zoom_scrollbars;
   bool use_pinch_virtual_viewport;