Fix potential NULL pointer in LayerTreeHostImpl

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index ff4ccf7e5b9bc526f807e76f1da705c6e52781d8..42258caf1579575daa9163b119699a4389d20b43 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -2206,10 +2206,11 @@ scoped_ptr<base::Value> LayerTreeHostImpl::AsValue() const {
 }
 
 scoped_ptr<base::Value> LayerTreeHostImpl::ActivationStateAsValue() const {
-  DCHECK(pending_tree_ && tile_manager_);
   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());
   state->Set("lthi", TracedValue::CreateIDRef(this).release());
-  state->Set("tile_manager", tile_manager_->BasicStateAsValue().release());
+  state->Set("tile_manager", tile_manager_ ?

[danakj, 2013/05/23 14:25:54]

Other places (AsValue() above this) just don't set a value when the thing is
missing. Can we do the same here instead of setting NULL?

[joth, 2013/05/23 19:46:17]

Done.

+      tile_manager_->BasicStateAsValue().release() :
+      new base::StringValue("NULL"));
   return state.PassAs<base::Value>();
 }