Refactor MutatorHostClient from LayerTreeHost to LayerTree.

cc/layers/layer_list_iterator_unittest.cc

Index: cc/layers/layer_list_iterator_unittest.cc
diff --git a/cc/layers/layer_list_iterator_unittest.cc b/cc/layers/layer_list_iterator_unittest.cc
index 457752dbc8adb2b91c3b75a27aa0d35727befb1f..57796842defb6bbdd35fc03db69f17d53c2a26fc 100644
--- a/cc/layers/layer_list_iterator_unittest.cc
+++ b/cc/layers/layer_list_iterator_unittest.cc
@@ -67,7 +67,7 @@ TEST(LayerListIteratorTest, VerifyTraversalOrder) {
   host->SetRootLayer(std::move(layer1));
 
   int i = 1;
-  for (auto* layer : *host) {
+  for (auto* layer : *host->GetLayerTree()) {
     EXPECT_EQ(i++, layer_id_to_order[layer->id()]);
   }
   EXPECT_EQ(8, i);
@@ -88,7 +88,7 @@ TEST(LayerListIteratorTest, VerifySingleLayer) {
   host->SetRootLayer(std::move(layer1));
 
   int i = 1;
-  for (auto* layer : *host) {
+  for (auto* layer : *host->GetLayerTree()) {
     EXPECT_EQ(i++, layer_id_to_order[layer->id()]);
   }
   EXPECT_EQ(2, i);
@@ -153,7 +153,7 @@ TEST(LayerListReverseIteratorTest, VerifyTraversalOrder) {
 
   int i = 7;
 
-  for (auto* layer : base::Reversed(*host)) {
+  for (auto* layer : base::Reversed(*host->GetLayerTree())) {
     EXPECT_EQ(i--, layer_id_to_order[layer->id()]);
   }
 
@@ -175,7 +175,7 @@ TEST(LayerListReverseIteratorTest, VerifySingleLayer) {
   host->SetRootLayer(std::move(layer1));
 
   int i = 1;
-  for (auto* layer : base::Reversed(*host)) {
+  for (auto* layer : base::Reversed(*host->GetLayerTree())) {
     EXPECT_EQ(i--, layer_id_to_order[layer->id()]);
   }
   EXPECT_EQ(0, i);