Copy damaged region when cloinng

Bug: 1134279
Test: covered by unittests
Change-Id: Ic8a411f57e8401321454f187dbcace2bd3c3c85d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2451709Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814240}

ui/compositor/layer.cc

@@ -281,6 +281,9 @@ std::unique_ptr<Layer> Layer::Clone() const {
   clone->SetIsFastRoundedCorner(is_fast_rounded_corner());
   clone->SetName(name_);
 
+  // the |damaged_region_| will be sent to cc later in SendDamagedRects().
+  clone->damaged_region_ = damaged_region_;
+
   return clone;
 }
 

ui/compositor/layer_unittest.cc

@@ -841,6 +841,25 @@ TEST_F(LayerWithDelegateTest, Cloning) {
   EXPECT_EQ(SK_ColorGREEN, clone->background_color());
 }
 
+TEST_F(LayerWithDelegateTest, CloneDamagedRegion) {
+  std::unique_ptr<Layer> layer = CreateLayer(LAYER_TEXTURED);
+  // Set a delegate so that the damage region is accumulated.
+  DrawTreeLayerDelegate delegate(gfx::Rect(0, 0, 10, 10));
+  layer->set_delegate(&delegate);
+
+  cc::Region damaged_region;
+  damaged_region.Union(gfx::Rect(10, 10, 5, 5));
+  damaged_region.Union(gfx::Rect(20, 20, 7, 7));
+
+  for (auto rect : damaged_region)
+    layer->SchedulePaint(rect);
+
+  ASSERT_EQ(damaged_region, layer->damaged_region());
+
+  auto clone = layer->Clone();
+  EXPECT_EQ(damaged_region, clone->damaged_region());
+}
+
 TEST_F(LayerWithDelegateTest, Mirroring) {
   std::unique_ptr<Layer> root = CreateNoTextureLayer(gfx::Rect(0, 0, 100, 100));
   std::unique_ptr<Layer> child = CreateLayer(LAYER_TEXTURED);