Handle ui::Layer's visibility using cc::Layer's m_isDrawable flag

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 fb32a9f7a5c96ba04539ef23022bd5cfdea793bd..011ad89f78cb480dd7c889d4f07ab5e0d4c418f6 100644
--- a/ui/compositor/layer_unittest.cc
+++ b/ui/compositor/layer_unittest.cc
@@ -629,9 +629,9 @@ TEST_F(LayerWithNullDelegateTest, Visibility) {
   EXPECT_TRUE(l1->IsDrawn());
   EXPECT_TRUE(l2->IsDrawn());
   EXPECT_TRUE(l3->IsDrawn());
-  EXPECT_EQ(1.f, l1->cc_layer()->opacity());
-  EXPECT_EQ(1.f, l2->cc_layer()->opacity());
-  EXPECT_EQ(1.f, l3->cc_layer()->opacity());
+  EXPECT_TRUE(l1->cc_layer()->drawsContent());
+  EXPECT_TRUE(l2->cc_layer()->drawsContent());
+  EXPECT_TRUE(l3->cc_layer()->drawsContent());
 
   compositor()->SetRootLayer(l1.get());
 
@@ -641,19 +641,25 @@ TEST_F(LayerWithNullDelegateTest, Visibility) {
   EXPECT_FALSE(l1->IsDrawn());
   EXPECT_FALSE(l2->IsDrawn());
   EXPECT_FALSE(l3->IsDrawn());
-  EXPECT_EQ(0.f, l1->cc_layer()->opacity());
+  EXPECT_FALSE(l1->cc_layer()->drawsContent());
+  EXPECT_FALSE(l2->cc_layer()->drawsContent());
+  EXPECT_FALSE(l3->cc_layer()->drawsContent());
 
   l3->SetVisible(false);
   EXPECT_FALSE(l1->IsDrawn());
   EXPECT_FALSE(l2->IsDrawn());
   EXPECT_FALSE(l3->IsDrawn());
-  EXPECT_EQ(0.f, l3->cc_layer()->opacity());
+  EXPECT_FALSE(l1->cc_layer()->drawsContent());
+  EXPECT_FALSE(l2->cc_layer()->drawsContent());
+  EXPECT_FALSE(l3->cc_layer()->drawsContent());
 
   l1->SetVisible(true);
   EXPECT_TRUE(l1->IsDrawn());
   EXPECT_TRUE(l2->IsDrawn());
   EXPECT_FALSE(l3->IsDrawn());
-  EXPECT_EQ(1.f, l1->cc_layer()->opacity());
+  EXPECT_TRUE(l1->cc_layer()->drawsContent());
+  EXPECT_TRUE(l2->cc_layer()->drawsContent());
+  EXPECT_FALSE(l3->cc_layer()->drawsContent());
 }
 
 // Checks that stacking-related methods behave as advertised.