cc: Switch eviction iterators to consider combined priority.

cc/resources/tile_manager.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/resources/tile_manager.h"
 
 #include <algorithm>
 #include <limits>
 #include <string>
 
@@ skipping 512 matching lines @@
     MemoryUsage* usage) {
   while (usage->Exceeds(limit)) {
     if (!eviction_priority_queue) {
       eviction_priority_queue =
           client_->BuildEvictionQueue(global_state_.tree_priority);
     }
     if (eviction_priority_queue->IsEmpty())
       break;
 
     Tile* tile = eviction_priority_queue->Top();
-    if (!other_priority.IsHigherPriorityThan(tile->combined_priority()))
+    const TilePriority& eviction_priority = tile->combined_priority();
+
+    // If eviction tile is strictly higher priority, then we can't evict.
+    if (eviction_priority.IsHigherPriorityThan(other_priority))
       break;
 
+    // If there's a tie in priority, prefer to the keep the eviction tile
+    // unless it's non ideal resolution or is occluded.
+    if (!tile->is_occluded_combined() &&
+        (eviction_priority.resolution != NON_IDEAL_RESOLUTION) &&

[danakj, 2015/02/12 23:48:46]

I think you should do this separately with a test to demonstrate it.

[vmpstr, 2015/02/12 23:52:34]

OK. Removed from this CL.

+        !other_priority.IsHigherPriorityThan(tile->combined_priority())) {
+      break;
+    }
+
     *usage -= MemoryUsage::FromTile(tile);
     FreeResourcesForTileAndNotifyClientIfTileWasReadyToDraw(tile);
     eviction_priority_queue->Pop();
   }
   return eviction_priority_queue;
 }
 
 bool TileManager::TilePriorityViolatesMemoryPolicy(
     const TilePriority& priority) {
   switch (global_state_.memory_limit_policy) {
@@ skipping 503 matching lines @@
   result -= other;
   return result;
 }
 
 bool TileManager::MemoryUsage::Exceeds(const MemoryUsage& limit) const {
   return memory_bytes_ > limit.memory_bytes_ ||
          resource_count_ > limit.resource_count_;
 }
 
 }  // namespace cc