Revert of cc: Remove tile sharing from tilings.

cc/trees/layer_tree_host_unittest_picture.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/trees/layer_tree_host.h"
 
 #include "cc/test/fake_content_layer_client.h"
 #include "cc/test/fake_picture_layer.h"
 #include "cc/test/fake_picture_layer_impl.h"
 #include "cc/test/layer_tree_test.h"
@@ skipping 224 matching lines @@
       case 1: {
         PictureLayerTiling* tiling = picture_impl->HighResTiling();
         PictureLayerTiling* recycled_tiling = recycled_impl->HighResTiling();
         int num_tiles_y = tiling->TilingDataForTesting().num_tiles_y();
 
         // There should be tiles at the top of the picture layer but not at the
         // bottom.
         EXPECT_TRUE(tiling->TileAt(0, 0));
         EXPECT_FALSE(tiling->TileAt(0, num_tiles_y));
 
-        // The recycled tiling has no tiles.
-        EXPECT_FALSE(recycled_tiling->TileAt(0, 0));
+        // The recycled tiling matches it.
+        EXPECT_TRUE(recycled_tiling->TileAt(0, 0));
         EXPECT_FALSE(recycled_tiling->TileAt(0, num_tiles_y));
 
         // The live tiles rect matches on the recycled tree.
         EXPECT_EQ(tiling->live_tiles_rect(),
                   recycled_tiling->live_tiles_rect());
 
         // Make the bottom of the layer visible.
         picture_impl->SetPosition(gfx::PointF(0.f, -100000.f + 100.f));
         impl->SetNeedsRedraw();
         break;
       }
       case 2: {
         PictureLayerTiling* tiling = picture_impl->HighResTiling();
         PictureLayerTiling* recycled_tiling = recycled_impl->HighResTiling();
 
         // There not be tiles at the top of the layer now.
         EXPECT_FALSE(tiling->TileAt(0, 0));
 
         // The recycled twin tiling should not have unshared tiles at the top
         // either.
         EXPECT_FALSE(recycled_tiling->TileAt(0, 0));
 
+        // The live tiles rect matches on the recycled tree.
+        EXPECT_EQ(tiling->live_tiles_rect(),
+                  recycled_tiling->live_tiles_rect());
+
         // Make the top of the layer visible again.
         picture_impl->SetPosition(gfx::PointF());
         impl->SetNeedsRedraw();
         break;
       }
       case 3: {
         PictureLayerTiling* tiling = picture_impl->HighResTiling();
         PictureLayerTiling* recycled_tiling = recycled_impl->HighResTiling();
         int num_tiles_y = tiling->TilingDataForTesting().num_tiles_y();
 
         // There should be tiles at the top of the picture layer again.
         EXPECT_TRUE(tiling->TileAt(0, 0));
         EXPECT_FALSE(tiling->TileAt(0, num_tiles_y));
 
-        // The recycled tiling should have no tiles.
-        EXPECT_FALSE(recycled_tiling->TileAt(0, 0));
+        // The recycled tiling should also have tiles at the top.
+        EXPECT_TRUE(recycled_tiling->TileAt(0, 0));
         EXPECT_FALSE(recycled_tiling->TileAt(0, num_tiles_y));
 
         // The live tiles rect matches on the recycled tree.
         EXPECT_EQ(tiling->live_tiles_rect(),
                   recycled_tiling->live_tiles_rect());
 
         // Make a new main frame without changing the picture layer at all, so
         // it won't need to update or push properties.
         did_post_commit_ = true;
         PostSetNeedsCommitToMainThread();
         break;
       }
     }
   }
 
   void WillActivateTreeOnThread(LayerTreeHostImpl* impl) override {
     LayerImpl* child = impl->sync_tree()->root_layer()->children()[0];
     FakePictureLayerImpl* picture_impl =
         static_cast<FakePictureLayerImpl*>(child);
     PictureLayerTiling* tiling = picture_impl->HighResTiling();
     int num_tiles_y = tiling->TilingDataForTesting().num_tiles_y();
 
-    if (!impl->active_tree()->root_layer()) {
-      // If active tree doesn't have the layer, then pending tree should have
-      // all needed tiles.
-      EXPECT_TRUE(tiling->TileAt(0, 0));
-    } else {
-      // Since there was no invalidation, the pending tree shouldn't have any
-      // tiles.
-      EXPECT_FALSE(tiling->TileAt(0, 0));
-    }
+    // The pending layer should always have tiles at the top of it each commit.
+    // The tile is part of the required for activation set so it should exist.
+    EXPECT_TRUE(tiling->TileAt(0, 0));
     EXPECT_FALSE(tiling->TileAt(0, num_tiles_y));
 
     if (did_post_commit_)
       EndTest();
   }
 
   void AfterTest() override {}
 
   int frame_;
   bool did_post_commit_;
@@ skipping 239 matching lines @@
   int last_frame_drawn_;
 };
 
 // Multi-thread only because in single thread you can't pinch zoom on the
 // compositor thread.
 // Disabled due to flakiness. See http://crbug.com/460581
 // MULTI_THREAD_IMPL_TEST_F(LayerTreeHostPictureTestRSLLMembershipWithScale);
 
 }  // namespace
 }  // namespace cc