cc: Use reverse spiral iterator in tiling eviction.

cc/layers/picture_layer_impl_perftest.cc

 // Copyright 2014 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 "cc/debug/lap_timer.h"
 #include "cc/test/fake_impl_proxy.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
 #include "cc/test/fake_output_surface.h"
@@ skipping 104 matching lines @@
                            true);
   }
 
   void RunEvictionIteratorConstructAndIterateTest(
       const std::string& test_name,
       int num_tiles,
       const gfx::Size& viewport_size) {
     host_impl_.SetViewportSize(viewport_size);
     host_impl_.pending_tree()->UpdateDrawProperties();
 
-    TreePriority priorities[] = {SAME_PRIORITY_FOR_BOTH_TREES,
-                                 SMOOTHNESS_TAKES_PRIORITY,
-                                 NEW_CONTENT_TAKES_PRIORITY};
-    int priority_count = 0;
     timer_.Reset();
     do {
       int count = num_tiles;
-      PictureLayerImpl::LayerEvictionTileIterator it(
-          pending_layer_, priorities[priority_count]);
+      PictureLayerImpl::LayerEvictionTileIterator it(pending_layer_);
       while (count--) {
         ASSERT_TRUE(it) << "count: " << count;
         ASSERT_TRUE(*it != nullptr) << "count: " << count;
         ++it;
       }
-      priority_count = (priority_count + 1) % arraysize(priorities);
       timer_.NextLap();
     } while (!timer_.HasTimeLimitExpired());
 
     perf_test::PrintResult("layer_eviction_tile_iterator_construct_and_iterate",
                            "",
                            test_name,
                            timer_.LapsPerSecond(),
                            "runs/s",
                            true);
   }
 
   void RunEvictionIteratorConstructTest(const std::string& test_name,
                                         const gfx::Rect& viewport) {
     host_impl_.SetViewportSize(viewport.size());
     pending_layer_->SetScrollOffset(
         gfx::ScrollOffset(viewport.x(), viewport.y()));
     host_impl_.pending_tree()->UpdateDrawProperties();
 
-    TreePriority priorities[] = {SAME_PRIORITY_FOR_BOTH_TREES,
-                                 SMOOTHNESS_TAKES_PRIORITY,
-                                 NEW_CONTENT_TAKES_PRIORITY};
-    int priority_count = 0;
     timer_.Reset();
     do {
-      PictureLayerImpl::LayerEvictionTileIterator it(
-          pending_layer_, priorities[priority_count]);
-      priority_count = (priority_count + 1) % arraysize(priorities);
+      PictureLayerImpl::LayerEvictionTileIterator it(pending_layer_);
       timer_.NextLap();
     } while (!timer_.HasTimeLimitExpired());
 
     perf_test::PrintResult("layer_eviction_tile_iterator_construct",
                            "",
                            test_name,
                            timer_.LapsPerSecond(),
                            "runs/s",
                            true);
   }
@@ skipping 90 matching lines @@
 
   RunEvictionIteratorConstructTest("0_0_100x100", gfx::Rect(0, 0, 100, 100));
   RunEvictionIteratorConstructTest("5000_0_100x100",
                                    gfx::Rect(5000, 0, 100, 100));
   RunEvictionIteratorConstructTest("9999_0_100x100",
                                    gfx::Rect(9999, 0, 100, 100));
 }
 
 }  // namespace
 }  // namespace cc