Refactor MutatorHostClient from LayerTreeHost to LayerTree.

cc/debug/invalidation_benchmark.cc

Index: cc/debug/invalidation_benchmark.cc
diff --git a/cc/debug/invalidation_benchmark.cc b/cc/debug/invalidation_benchmark.cc
index 681e29ef7cced1b62c1f9303d22c0c26df7494af..745d1f8cdfe1579a1db831e3ebdf8bf4695ef350 100644
--- a/cc/debug/invalidation_benchmark.cc
+++ b/cc/debug/invalidation_benchmark.cc
@@ -65,7 +65,8 @@ InvalidationBenchmark::~InvalidationBenchmark() {
 
 void InvalidationBenchmark::DidUpdateLayers(LayerTreeHost* host) {

[Khushal, 2016/08/15 17:46:39]

How about updating the MicroBenchmark interface to take a LayerTree itself here?

[xingliu, 2016/08/15 21:29:12]

I think it makes sense, and there isn't too much work for this refactoring, but
maybe we can do it in a separate CL? since it's like modify an interface in
cc/debug.

   LayerTreeHostCommon::CallFunctionForEveryLayer(
-      host, [this](Layer* layer) { layer->RunMicroBenchmark(this); });
+      host->GetLayerTree(),
+      [this](Layer* layer) { layer->RunMicroBenchmark(this); });
 }
 
 void InvalidationBenchmark::RunOnLayer(PictureLayer* layer) {