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

cc/layers/picture_layer_impl.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 
@@ skipping 646 matching lines @@
 }
 
 PictureLayerTiling* PictureLayerImpl::GetRecycledTwinTiling(
     const PictureLayerTiling* tiling) {
   PictureLayerImpl* recycled_twin = GetRecycledTwinLayer();
   if (!recycled_twin || !recycled_twin->tilings_)
     return nullptr;
   return recycled_twin->tilings_->TilingAtScale(tiling->contents_scale());
 }
 
+TilePriority::PriorityBin PictureLayerImpl::GetMaxTilePriorityBin() const {
+  if (!HasValidTilePriorities())
+    return TilePriority::EVENTUALLY;
+  return TilePriority::NOW;
+}
+
 size_t PictureLayerImpl::GetMaxTilesForInterestArea() const {
   return layer_tree_impl()->settings().max_tiles_for_interest_area;
 }
 
 float PictureLayerImpl::GetSkewportTargetTimeInSeconds() const {
   float skewport_target_time_in_frames =
       layer_tree_impl()->use_gpu_rasterization()
           ? kGpuSkewportTargetTimeInFrames
           : kCpuSkewportTargetTimeInFrames;
   return skewport_target_time_in_frames *
@@ skipping 889 matching lines @@
       current_tiling_(0u) {
 }
 
 PictureLayerImpl::LayerEvictionTileIterator::LayerEvictionTileIterator(
     PictureLayerImpl* layer,
     TreePriority tree_priority)
     : layer_(layer),
       tree_priority_(tree_priority),
       current_category_(PictureLayerTiling::EVENTUALLY),
       current_tiling_range_type_(PictureLayerTilingSet::HIGHER_THAN_HIGH_RES),
-      current_tiling_(CurrentTilingRange().start - 1u) {
-  // TODO(vmpstr): Once tile priorities are determined by the iterators, ensure
-  // that layers that don't have valid tile priorities have lowest priorities so
-  // they evict their tiles first (crbug.com/381704)
-  DCHECK(layer_->tilings_);
+      current_tiling_(0u) {
+  // Early out if the layer has no tilings.
+  if (!layer_->tilings_ || !layer_->tilings_->num_tilings())
+    return;
+
+  current_tiling_ = CurrentTilingRange().start - 1u;
   do {
     if (!AdvanceToNextTiling())
       break;
 
     current_iterator_ = PictureLayerTiling::TilingEvictionTileIterator(
         layer_->tilings_->tiling_at(CurrentTilingIndex()),
         tree_priority,
         current_category_);
   } while (!current_iterator_);
 }
@@ skipping 114 matching lines @@
       PictureLayerTilingSet::TilingRange tiling_range = CurrentTilingRange();
       size_t current_tiling_range_offset = current_tiling_ - tiling_range.start;
       return tiling_range.end - 1 - current_tiling_range_offset;
     }
   }
   NOTREACHED();
   return 0;
 }
 
 }  // namespace cc