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

cc/layers/picture_layer_impl_perftest.cc

Index: cc/layers/picture_layer_impl_perftest.cc
diff --git a/cc/layers/picture_layer_impl_perftest.cc b/cc/layers/picture_layer_impl_perftest.cc
index aeea2bb7fee2f8f68623911711864c12755bb6df..686f6fdfcefe2472c0ee80835d51c6599e36edf2 100644
--- a/cc/layers/picture_layer_impl_perftest.cc
+++ b/cc/layers/picture_layer_impl_perftest.cc
@@ -130,7 +130,7 @@ class PictureLayerImplPerfTest : public testing::Test {
     do {
       int count = num_tiles;
       PictureLayerImpl::LayerEvictionTileIterator it(
-          pending_layer_, priorities[priority_count]);
+          pending_layer_, nullptr, priorities[priority_count]);
       while (count--) {
         ASSERT_TRUE(it) << "count: " << count;
         ASSERT_TRUE(*it != nullptr) << "count: " << count;
@@ -162,7 +162,7 @@ class PictureLayerImplPerfTest : public testing::Test {
     timer_.Reset();
     do {
       PictureLayerImpl::LayerEvictionTileIterator it(
-          pending_layer_, priorities[priority_count]);
+          pending_layer_, nullptr, priorities[priority_count]);
       priority_count = (priority_count + 1) % arraysize(priorities);
       timer_.NextLap();
     } while (!timer_.HasTimeLimitExpired());