cc: Indicate that we've updated a tiling if we invalidated it.

cc/tiles/picture_layer_tiling_unittest.cc

Index: cc/tiles/picture_layer_tiling_unittest.cc
diff --git a/cc/tiles/picture_layer_tiling_unittest.cc b/cc/tiles/picture_layer_tiling_unittest.cc
index 40f288fcd364288b347a9d4a1f0a8ff646bd0a54..8129bc0eab294537a9037e8c79af3a73f8f4e110 100644
--- a/cc/tiles/picture_layer_tiling_unittest.cc
+++ b/cc/tiles/picture_layer_tiling_unittest.cc
@@ -1784,6 +1784,26 @@ TEST(PictureLayerTilingTest, RecycledTilesClearedOnReset) {
   EXPECT_FALSE(recycle_tiling->TileAt(0, 0));
 }
 
+TEST(PictureLayerTilingTest, InvalidateAfterComputeTilePriorityRects) {

[enne (OOO), 2016/04/04 18:43:51]

WTB a comment for the scenario that this is testing.

[vmpstr, 2016/04/04 19:45:29]

Done.

+  FakePictureLayerTilingClient pending_client;
+  pending_client.SetTileSize(gfx::Size(100, 100));
+
+  scoped_refptr<FakeRasterSource> raster_source =
+      FakeRasterSource::CreateFilled(gfx::Size(100, 100));
+  scoped_ptr<TestablePictureLayerTiling> pending_tiling =
+      TestablePictureLayerTiling::Create(PENDING_TREE, 1.0f, raster_source,
+                                         &pending_client, LayerTreeSettings());
+  pending_tiling->set_resolution(HIGH_RESOLUTION);
+
+  double time = 1.;
+  gfx::Rect viewport(0, 0, 100, 100);
+  EXPECT_TRUE(pending_tiling->ComputeTilePriorityRects(viewport, 1.0f, time,
+                                                       Occlusion()));
+  pending_tiling->Invalidate(viewport);
+  EXPECT_TRUE(pending_tiling->ComputeTilePriorityRects(viewport, 1.0f, time,
+                                                       Occlusion()));
+}
+
 TEST_F(PictureLayerTilingIteratorTest, ResizeTilesAndUpdateToCurrent) {
   // The tiling has four rows and three columns.
   Initialize(gfx::Size(150, 100), 1.f, gfx::Size(250, 150));