cc: Always keep the PictureLayerImpl::twin_layer_ pointer valid.

cc/layers/picture_layer_impl_unittest.cc

 // Copyright 2013 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>
 #include <utility>
@@ skipping 120 matching lines @@
       active_layer_->tilings()->tiling_at(i)->CreateAllTilesForTesting();
     pending_layer_->set_invalidation(invalidation);
     for (size_t i = 0; i < pending_layer_->tilings()->num_tilings(); ++i)
       pending_layer_->tilings()->tiling_at(i)->CreateAllTilesForTesting();
   }
 
   void SetupPendingTree(scoped_refptr<PicturePileImpl> pile) {
     host_impl_.CreatePendingTree();
     host_impl_.pending_tree()->SetPageScaleFactorAndLimits(1.f, 0.25f, 100.f);
     LayerTreeImpl* pending_tree = host_impl_.pending_tree();
-    // Clear recycled tree.
-    pending_tree->DetachLayerTree();
 
-    scoped_ptr<FakePictureLayerImpl> pending_layer =
-        FakePictureLayerImpl::CreateWithPile(pending_tree, id_, pile);
-    pending_layer->SetDrawsContent(true);
+    // Steal from the recycled tree.
+    scoped_ptr<LayerImpl> old_pending_root = pending_tree->DetachLayerTree();
+    DCHECK_IMPLIES(old_pending_root, old_pending_root->id() == id_);
+
+    scoped_ptr<FakePictureLayerImpl> pending_layer;
+    if (old_pending_root) {
+      pending_layer.reset(
+          static_cast<FakePictureLayerImpl*>(old_pending_root.release()));
+      pending_layer->SetPile(pile);
+    } else {
+      pending_layer =
+          FakePictureLayerImpl::CreateWithPile(pending_tree, id_, pile);
+      pending_layer->SetDrawsContent(true);
+    }
+    // The bounds() just mirror the pile size.
+    pending_layer->SetBounds(pending_layer->pile()->tiling_size());
     pending_tree->SetRootLayer(pending_layer.Pass());
 
     pending_layer_ = static_cast<FakePictureLayerImpl*>(
         host_impl_.pending_tree()->LayerById(id_));
     pending_layer_->DoPostCommitInitializationIfNeeded();
   }
 
   void SetupDrawPropertiesAndUpdateTiles(FakePictureLayerImpl* layer,
                                          float ideal_contents_scale,
                                          float device_scale_factor,
@@ skipping 2050 matching lines @@
 
   pending_layer_->tilings()->RemoveAllTilings();
   ASSERT_EQ(0u, pending_layer_->tilings()->num_tilings());
 
   // Now, set the bounds to be 1x1 (so that minimum contents scale becomes
   // 1.0f). Note that we should also ensure that the pending layer needs post
   // commit initialization, since this is what would happen during commit. In
   // other words we want the pending layer to sync from the active layer.
   pending_layer_->SetBounds(gfx::Size(1, 1));
   pending_layer_->SetNeedsPostCommitInitialization();
-  pending_layer_->set_twin_layer(nullptr);
-  active_layer_->set_twin_layer(nullptr);
   EXPECT_TRUE(pending_layer_->needs_post_commit_initialization());
 
   // Update the draw properties: sync from active tree should happen here.
   host_impl_.pending_tree()->UpdateDrawProperties();
+  EXPECT_FALSE(pending_layer_->needs_post_commit_initialization());
 
   // Another sanity check.
   ASSERT_EQ(1.f, pending_layer_->MinimumContentsScale());
 
   // Now we should've synced 1.5f tiling, since that's the only one that doesn't
   // violate minimum contents scale. At the same time, we should've created a
   // new high res tiling at scale 1.0f.
   EXPECT_EQ(2u, pending_layer_->tilings()->num_tilings());
   ASSERT_TRUE(pending_layer_->tilings()->TilingAtScale(1.0f));
   EXPECT_EQ(HIGH_RESOLUTION,
@@ skipping 1869 matching lines @@
              gfx::Rect(layer_bounds));
          iter;
          ++iter) {
       if (!*iter)
         continue;
       const Tile* tile = *iter;
 
       // All tiles are unoccluded on the pending tree.
       EXPECT_FALSE(tile->is_occluded(PENDING_TREE));
 
-      Tile* twin_tile =
-          pending_layer_->GetTwinTiling(tiling)->TileAt(iter.i(), iter.j());
+      Tile* twin_tile = pending_layer_->GetPendingOrActiveTwinTiling(tiling)
+                            ->TileAt(iter.i(), iter.j());
       gfx::Rect scaled_content_rect = ScaleToEnclosingRect(
           tile->content_rect(), 1.0f / tile->contents_scale());
 
       if (scaled_content_rect.Intersects(invalidation_rect)) {
         // Tiles inside the invalidation rect are only on the pending tree.
         EXPECT_NE(tile, twin_tile);
 
         // Unshared tiles should be unoccluded on the active tree by default.
         EXPECT_FALSE(tile->is_occluded(ACTIVE_TREE));
       } else {
@@ skipping 13 matching lines @@
     for (PictureLayerTiling::CoverageIterator iter(
              tiling,
              active_layer_->contents_scale_x(),
              gfx::Rect(layer_bounds));
          iter;
          ++iter) {
       if (!*iter)
         continue;
       const Tile* tile = *iter;
 
-      Tile* twin_tile =
-          active_layer_->GetTwinTiling(tiling)->TileAt(iter.i(), iter.j());
+      Tile* twin_tile = active_layer_->GetPendingOrActiveTwinTiling(tiling)
+                            ->TileAt(iter.i(), iter.j());
       gfx::Rect scaled_content_rect = ScaleToEnclosingRect(
           tile->content_rect(), 1.0f / tile->contents_scale());
 
       // Since we've already checked the shared tiles, only consider tiles in
       // the invalidation rect.
       if (scaled_content_rect.Intersects(invalidation_rect)) {
         // Tiles inside the invalidation rect are only on the active tree.
         EXPECT_NE(tile, twin_tile);
 
         // Unshared tiles should be unoccluded on the pending tree by default.
@@ skipping 156 matching lines @@
   }
 
   host_impl_.tile_manager()->InitializeTilesWithResourcesForTesting(all_tiles);
 
   VerifyEvictionConsidersOcclusion(pending_layer_,
                                    total_expected_occluded_tile_count);
   VerifyEvictionConsidersOcclusion(active_layer_,
                                    total_expected_occluded_tile_count);
 }
 
+TEST_F(PictureLayerImplTest, PendingOrActiveTwinLayer) {
+  gfx::Size tile_size(102, 102);
+  gfx::Size layer_bounds(1000, 1000);
+
+  scoped_refptr<FakePicturePileImpl> pile =
+      FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
+  SetupPendingTree(pile);
+  EXPECT_FALSE(pending_layer_->GetPendingOrActiveTwinLayer());
+
+  ActivateTree();
+  EXPECT_FALSE(active_layer_->GetPendingOrActiveTwinLayer());
+
+  SetupPendingTree(pile);
+  EXPECT_TRUE(pending_layer_->GetPendingOrActiveTwinLayer());
+  EXPECT_TRUE(active_layer_->GetPendingOrActiveTwinLayer());
+  EXPECT_EQ(pending_layer_, active_layer_->GetPendingOrActiveTwinLayer());
+  EXPECT_EQ(active_layer_, pending_layer_->GetPendingOrActiveTwinLayer());
+
+  ActivateTree();
+  EXPECT_FALSE(active_layer_->GetPendingOrActiveTwinLayer());
+
+  // Make an empty pending tree.
+  host_impl_.CreatePendingTree();
+  host_impl_.pending_tree()->DetachLayerTree();
+  EXPECT_FALSE(active_layer_->GetPendingOrActiveTwinLayer());
+}
+
 TEST_F(PictureLayerImplTest, RecycledTwinLayer) {
   gfx::Size tile_size(102, 102);
   gfx::Size layer_bounds(1000, 1000);
 
   scoped_refptr<FakePicturePileImpl> pile =
       FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
   SetupPendingTree(pile);
   EXPECT_FALSE(pending_layer_->GetRecycledTwinLayer());
 
   ActivateTree();
   EXPECT_TRUE(active_layer_->GetRecycledTwinLayer());
   EXPECT_EQ(old_pending_layer_, active_layer_->GetRecycledTwinLayer());
 
   SetupPendingTree(pile);
   EXPECT_FALSE(pending_layer_->GetRecycledTwinLayer());
   EXPECT_FALSE(active_layer_->GetRecycledTwinLayer());
 
   ActivateTree();
   EXPECT_TRUE(active_layer_->GetRecycledTwinLayer());
   EXPECT_EQ(old_pending_layer_, active_layer_->GetRecycledTwinLayer());
 
-  host_impl_.ResetRecycleTreeForTesting();
+  // Make an empty pending tree.
+  host_impl_.CreatePendingTree();
+  host_impl_.pending_tree()->DetachLayerTree();
   EXPECT_FALSE(active_layer_->GetRecycledTwinLayer());
 }
 
 void PictureLayerImplTest::TestQuadsForSolidColor(bool test_for_solid) {
   base::TimeTicks time_ticks;
   time_ticks += base::TimeDelta::FromMilliseconds(1);
   host_impl_.SetCurrentBeginFrameArgs(
       CreateBeginFrameArgsForTesting(time_ticks));
 
   gfx::Size tile_size(100, 100);
@@ skipping 256 matching lines @@
   result = layer->CalculateTileSize(gfx::Size(447, 400));
   EXPECT_EQ(result.width(), 448);
   EXPECT_EQ(result.height(), 448);
   result = layer->CalculateTileSize(gfx::Size(500, 499));
   EXPECT_EQ(result.width(), 512);
   EXPECT_EQ(result.height(), 500 + 2);
 }
 
 }  // namespace
 }  // namespace cc