Split picture layer quads to allow removing more occluded area.

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 <stddef.h>
 
 #include <algorithm>
 #include <limits>
@@ skipping 3084 matching lines @@
     LayerTestCommon::VerifyQuadsExactlyCoverRect(impl.quad_list(), gfx::Rect());
     EXPECT_EQ(impl.quad_list().size(), 0u);
   }
 
   {
     SCOPED_TRACE("Partial occlusion");
     gfx::Rect occluded(150, 0, 200, 1000);
     impl.AppendQuadsWithOcclusion(active_layer(), occluded);
 
     size_t partially_occluded_count = 0;
-    LayerTestCommon::VerifyQuadsAreOccluded(
-        impl.quad_list(), occluded, &partially_occluded_count);
+    LayerTestCommon::VerifyQuadsAreOccluded(impl.quad_list(), occluded, true,
+                                            &partially_occluded_count);
     // The layer outputs one quad, which is partially occluded.
     EXPECT_EQ(100u - 10u, impl.quad_list().size());
     EXPECT_EQ(10u + 10u, partially_occluded_count);
   }
+
+  {
+    SCOPED_TRACE("Central occlusion");
+    gfx::Rect occluded(150, 50, 200, 900);
+    impl.AppendQuadsWithOcclusion(active_layer(), occluded);
+
+    size_t partially_occluded_count = 0;
+    LayerTestCommon::VerifyQuadsAreOccluded(impl.quad_list(), occluded, true,
+                                            &partially_occluded_count);
+    // 8 quads in the middle are removed completely. 10 on the left and 10 on
+    // the right are occluded, as 1 on the top and 1 on the bottom. The four
+    // corners of the occluded region are each split into 2 quads.
+    EXPECT_EQ(100u - 8u + 4u, impl.quad_list().size());
+    EXPECT_EQ(10u + 10u + 4u + 2u, partially_occluded_count);
+  }
 }
 
 TEST_F(PictureLayerImplTest, RasterScaleChangeWithoutAnimation) {
   gfx::Size tile_size(host_impl()->settings().default_tile_size);
   SetupDefaultTrees(tile_size);
 
   ResetTilingsAndRasterScales();
 
   float contents_scale = 2.f;
   float device_scale = 1.f;
@@ skipping 2026 matching lines @@
     EXPECT_EQ(gfx::AxisTransform2d(2.25f, gfx::Vector2dF(0.75f, 0.25f)),
               tiling->raster_transform());
     EXPECT_EQ(4u, tiling->AllTilesForTesting().size());
     for (auto* tile : tiling->AllTilesForTesting())
       EXPECT_EQ(tile->raster_transform(), tiling->raster_transform());
   }
 }
 
 }  // namespace
 }  // namespace cc