cc: Do not ignore layers without valid priorities during eviction.

cc/layers/picture_layer_impl_unittest.cc

Index: cc/layers/picture_layer_impl_unittest.cc
diff --git a/cc/layers/picture_layer_impl_unittest.cc b/cc/layers/picture_layer_impl_unittest.cc
index 6b2d4c9c6c3438c2c7684675b624903d4b4ed48f..67001fd1a1fc316af86d6383cf6b022334695a82 100644
--- a/cc/layers/picture_layer_impl_unittest.cc
+++ b/cc/layers/picture_layer_impl_unittest.cc
@@ -2944,7 +2944,7 @@ TEST_F(PictureLayerImplTest, LayerEvictionTileIterator) {
 
   // Tiles don't have resources yet.
   it = PictureLayerImpl::LayerEvictionTileIterator(
-      pending_layer_, SAME_PRIORITY_FOR_BOTH_TREES);
+      pending_layer_, nullptr, SAME_PRIORITY_FOR_BOTH_TREES);
   EXPECT_FALSE(it);
 
   host_impl_.tile_manager()->InitializeTilesWithResourcesForTesting(all_tiles);
@@ -2955,7 +2955,7 @@ TEST_F(PictureLayerImplTest, LayerEvictionTileIterator) {
   bool reached_visible = false;
   Tile* last_tile = nullptr;
   for (it = PictureLayerImpl::LayerEvictionTileIterator(
-           pending_layer_, SAME_PRIORITY_FOR_BOTH_TREES);
+           pending_layer_, nullptr, SAME_PRIORITY_FOR_BOTH_TREES);
        it;
        ++it) {
     Tile* tile = *it;
@@ -3807,6 +3807,7 @@ class OcclusionTrackingPictureLayerImplTest : public PictureLayerImplTest {
 
   void VerifyEvictionConsidersOcclusion(
       PictureLayerImpl* layer,
+      const PictureLayerImpl* twin_layer,
       size_t expected_occluded_tile_count[NUM_TREE_PRIORITIES]) {
     for (int priority_count = 0; priority_count < NUM_TREE_PRIORITIES;
          ++priority_count) {
@@ -3815,8 +3816,8 @@ class OcclusionTrackingPictureLayerImplTest : public PictureLayerImplTest {
       Tile* last_tile = nullptr;
 
       for (PictureLayerImpl::LayerEvictionTileIterator it =
-               PictureLayerImpl::LayerEvictionTileIterator(layer,
-                                                           tree_priority);
+               PictureLayerImpl::LayerEvictionTileIterator(
+                   layer, twin_layer, tree_priority);
            it;
            ++it) {
         Tile* tile = *it;
@@ -4410,10 +4411,10 @@ TEST_F(OcclusionTrackingPictureLayerImplTest,
 
   host_impl_.tile_manager()->InitializeTilesWithResourcesForTesting(all_tiles);
 
-  VerifyEvictionConsidersOcclusion(pending_layer_,
-                                   total_expected_occluded_tile_count);
-  VerifyEvictionConsidersOcclusion(active_layer_,
-                                   total_expected_occluded_tile_count);
+  VerifyEvictionConsidersOcclusion(
+      pending_layer_, active_layer_, total_expected_occluded_tile_count);
+  VerifyEvictionConsidersOcclusion(
+      active_layer_, pending_layer_, total_expected_occluded_tile_count);
 }
 
 TEST_F(PictureLayerImplTest, PendingOrActiveTwinLayer) {