Compute if a layer is drawn without LayerTree hierarchy

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 d9f5a7a08dbf68dc6e5dcf3d1528975b9df6ab49..ca3c2d6f2b9a4fbdbe25d620be8ec12e91212dc4 100644
--- a/ui/compositor/layer_unittest.cc
+++ b/ui/compositor/layer_unittest.cc
@@ -727,7 +727,7 @@ TEST_F(LayerWithNullDelegateTest, SwitchLayerPreservesCCLayerState) {
   EXPECT_TRUE(l1->cc_layer_for_testing()->DrawsContent());
   EXPECT_TRUE(l1->cc_layer_for_testing()->contents_opaque());
   EXPECT_TRUE(l1->cc_layer_for_testing()->force_render_surface());
-  EXPECT_TRUE(l1->cc_layer_for_testing()->hide_layer_and_subtree());
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.f);
   EXPECT_EQ(gfx::Size(4, 5), l1->cc_layer_for_testing()->bounds());
 
   cc::Layer* before_layer = l1->cc_layer_for_testing();
@@ -744,7 +744,7 @@ TEST_F(LayerWithNullDelegateTest, SwitchLayerPreservesCCLayerState) {
   EXPECT_TRUE(l1->cc_layer_for_testing()->DrawsContent());
   EXPECT_TRUE(l1->cc_layer_for_testing()->contents_opaque());
   EXPECT_TRUE(l1->cc_layer_for_testing()->force_render_surface());
-  EXPECT_TRUE(l1->cc_layer_for_testing()->hide_layer_and_subtree());
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.f);
   EXPECT_EQ(gfx::Size(4, 5), l1->cc_layer_for_testing()->bounds());
   EXPECT_FALSE(callback1_run);
 
@@ -762,7 +762,7 @@ TEST_F(LayerWithNullDelegateTest, SwitchLayerPreservesCCLayerState) {
   EXPECT_TRUE(l1->cc_layer_for_testing()->DrawsContent());
   EXPECT_TRUE(l1->cc_layer_for_testing()->contents_opaque());
   EXPECT_TRUE(l1->cc_layer_for_testing()->force_render_surface());
-  EXPECT_TRUE(l1->cc_layer_for_testing()->hide_layer_and_subtree());
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.f);
   EXPECT_EQ(gfx::Size(4, 5), l1->cc_layer_for_testing()->bounds());
   EXPECT_TRUE(callback2_run);
 
@@ -781,7 +781,7 @@ TEST_F(LayerWithNullDelegateTest, SwitchLayerPreservesCCLayerState) {
   EXPECT_TRUE(l1->cc_layer_for_testing()->DrawsContent());
   EXPECT_TRUE(l1->cc_layer_for_testing()->contents_opaque());
   EXPECT_TRUE(l1->cc_layer_for_testing()->force_render_surface());
-  EXPECT_TRUE(l1->cc_layer_for_testing()->hide_layer_and_subtree());
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.f);
   EXPECT_EQ(gfx::Size(4, 5), l1->cc_layer_for_testing()->bounds());
   EXPECT_FALSE(callback3_run);
 
@@ -806,9 +806,9 @@ TEST_F(LayerWithNullDelegateTest, Visibility) {
   EXPECT_TRUE(l1->IsDrawn());
   EXPECT_TRUE(l2->IsDrawn());
   EXPECT_TRUE(l3->IsDrawn());
-  EXPECT_FALSE(l1->cc_layer_for_testing()->hide_layer_and_subtree());
-  EXPECT_FALSE(l2->cc_layer_for_testing()->hide_layer_and_subtree());
-  EXPECT_FALSE(l3->cc_layer_for_testing()->hide_layer_and_subtree());
+  EXPECT_NE(l1->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_NE(l2->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_NE(l3->cc_layer_for_testing()->opacity(), 0.f);
 
   compositor()->SetRootLayer(l1.get());
 
@@ -818,25 +818,62 @@ TEST_F(LayerWithNullDelegateTest, Visibility) {
   EXPECT_FALSE(l1->IsDrawn());
   EXPECT_FALSE(l2->IsDrawn());
   EXPECT_FALSE(l3->IsDrawn());
-  EXPECT_TRUE(l1->cc_layer_for_testing()->hide_layer_and_subtree());
-  EXPECT_FALSE(l2->cc_layer_for_testing()->hide_layer_and_subtree());
-  EXPECT_FALSE(l3->cc_layer_for_testing()->hide_layer_and_subtree());
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_NE(l2->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_NE(l3->cc_layer_for_testing()->opacity(), 0.f);
 
   l3->SetVisible(false);
   EXPECT_FALSE(l1->IsDrawn());
   EXPECT_FALSE(l2->IsDrawn());
   EXPECT_FALSE(l3->IsDrawn());
-  EXPECT_TRUE(l1->cc_layer_for_testing()->hide_layer_and_subtree());
-  EXPECT_FALSE(l2->cc_layer_for_testing()->hide_layer_and_subtree());
-  EXPECT_TRUE(l3->cc_layer_for_testing()->hide_layer_and_subtree());
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_NE(l2->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_EQ(l3->cc_layer_for_testing()->opacity(), 0.f);
 
   l1->SetVisible(true);
   EXPECT_TRUE(l1->IsDrawn());
   EXPECT_TRUE(l2->IsDrawn());
   EXPECT_FALSE(l3->IsDrawn());
-  EXPECT_FALSE(l1->cc_layer_for_testing()->hide_layer_and_subtree());
-  EXPECT_FALSE(l2->cc_layer_for_testing()->hide_layer_and_subtree());
-  EXPECT_TRUE(l3->cc_layer_for_testing()->hide_layer_and_subtree());
+  EXPECT_NE(l1->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_NE(l2->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_EQ(l3->cc_layer_for_testing()->opacity(), 0.f);
+}
+
+TEST_F(LayerWithNullDelegateTest, CacheOpacityWhenLayerVisibilityChanges) {
+  scoped_ptr<Layer> l1(new Layer(LAYER_TEXTURED));
+
+  NullLayerDelegate delegate;
+  l1->set_delegate(&delegate);
+
+  // Initially, the layer should be fully opaque.
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 1.f);
+
+  compositor()->SetRootLayer(l1.get());
+
+  Draw();
+
+  // When a layer is invisble, the corresponding cc_layer should be completely
+  // transparent, but the ui layer should store the original opacity of cc
+  // layer.
+  l1->SetVisible(false);
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_EQ(l1->opacity(), 1.f);
+
+  // Any changes to opacity when the layer is invisble is cached by the  ui
+  // layer and set on the corresponding cc layer only when it becomes visible.
+  l1->SetOpacity(0.5f);
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.f);
+  EXPECT_EQ(l1->opacity(), 0.5f);
+  l1->SetVisible(true);
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.5f);
+
+  // The original opacity should be restored when invisible layer becomes
+  // visible.
+  l1->SetOpacity(0.2f);
+  l1->SetVisible(false);
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.f);
+  l1->SetVisible(true);
+  EXPECT_EQ(l1->cc_layer_for_testing()->opacity(), 0.2f);
 }
 
 // Checks that stacking-related methods behave as advertised.