cc: Fix size_t to int truncations in tiles/ and trees/

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index af3fc67471c847f0d6fbaf5dadc00d0838b983e5..760728cfad692adca38f889c2b2911f6e81a353d 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -40,7 +40,7 @@ scoped_refptr<Layer> Layer::Create(const LayerSettings& settings) {
 
 Layer::Layer(const LayerSettings& settings)
     : needs_push_properties_(false),
-      num_dependents_need_push_properties_(false),
+      num_dependents_need_push_properties_(0u),
       stacking_order_changed_(false),
       // Layer IDs start from 1.
       layer_id_(g_next_layer_id.GetNext() + 1),
@@ -209,8 +209,6 @@ void Layer::SetNeedsPushProperties() {
 }
 
 void Layer::AddDependentNeedsPushProperties() {
-  DCHECK_GE(num_dependents_need_push_properties_, 0);
-
   if (!parent_should_know_need_push_properties() && parent_)
     parent_->AddDependentNeedsPushProperties();
 
@@ -218,8 +216,8 @@ void Layer::AddDependentNeedsPushProperties() {
 }
 
 void Layer::RemoveDependentNeedsPushProperties() {
+  DCHECK_GT(num_dependents_need_push_properties_, 0u);
   num_dependents_need_push_properties_--;
-  DCHECK_GE(num_dependents_need_push_properties_, 0);
 
   if (!parent_should_know_need_push_properties() && parent_)
       parent_->RemoveDependentNeedsPushProperties();