Split picture layer quads to allow removing more occluded area.

cc/layers/picture_layer_impl_unittest.cc

Index: cc/layers/picture_layer_impl_unittest.cc
diff --git a/cc/layers/picture_layer_impl_unittest.cc b/cc/layers/picture_layer_impl_unittest.cc
index 6b326b8c96a9760207574dad21cdfd88ece48b34..894c4a45dcc820ed0153b0b3e07a184847c707c0 100644
--- a/cc/layers/picture_layer_impl_unittest.cc
+++ b/cc/layers/picture_layer_impl_unittest.cc
@@ -3102,12 +3102,27 @@ TEST_F(PictureLayerImplTest, Occlusion) {
     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) {