Clear ui::Layer damaged_region_ after commit.

ui/compositor/layer_unittest.cc

Index: ui/compositor/layer_unittest.cc
diff --git a/ui/compositor/layer_unittest.cc b/ui/compositor/layer_unittest.cc
index f24ad4659b42b8c3078d943566fed31b3cbc8fc9..6584ce1068f56fc858fe921d79a6c8e0a6606170 100644
--- a/ui/compositor/layer_unittest.cc
+++ b/ui/compositor/layer_unittest.cc
@@ -926,6 +926,30 @@ TEST_F(LayerWithNullDelegateTest, SetBoundsSchedulesPaint) {
   WaitForDraw();
 }
 
+// Checks that the damage rect for a TextureLayer is empty after a commit.
+TEST_F(LayerWithNullDelegateTest, EmptyDamagedRect) {
+  std::unique_ptr<Layer> root(CreateLayer(LAYER_SOLID_COLOR));
+  cc::TextureMailbox mailbox(gpu::Mailbox::Generate(), gpu::SyncToken(), 0);
+  bool callback_run = false;
+  root->SetTextureMailbox(mailbox, cc::SingleReleaseCallback::Create(base::Bind(
+                                       ReturnMailbox, &callback_run)),
+                          gfx::Size(10, 10));
+  compositor()->SetRootLayer(root.get());
+
+  root->SetBounds(gfx::Rect(0, 0, 10, 10));
+  root->SetVisible(true);
+  WaitForCommit();
+
+  gfx::Rect damaged_rect(0, 0, 5, 5);
+  root->SchedulePaint(damaged_rect);
+  EXPECT_EQ(damaged_rect,
+            root->damaged_region_for_testing()->bounds());
+  WaitForCommit();
+  EXPECT_TRUE(root->damaged_region_for_testing()->IsEmpty());
+
+  compositor()->SetRootLayer(nullptr);
+}
+
 void ExpectRgba(int x, int y, SkColor expected_color, SkColor actual_color) {
   EXPECT_EQ(expected_color, actual_color)
       << "Pixel error at x=" << x << " y=" << y << "; "