[cc] Consolidate UI resource destruction and recreation

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 870b65d89ba7b123085028c34359d4afbf122131..03d35893936dcdc64e51266601b8393b071e6e43 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1563,8 +1563,7 @@ void LayerTreeHostImpl::ReleaseTreeResources() {
   if (recycle_tree_ && recycle_tree_->root_layer())
     SendReleaseResourcesRecursive(recycle_tree_->root_layer());
 
-  // Remove all existing maps from UIResourceId to ResourceId.
-  ui_resource_map_.clear();
+  DeleteAllUIResources();
 }
 
 void LayerTreeHostImpl::CreateAndSetRenderer(
@@ -2575,6 +2574,15 @@ void LayerTreeHostImpl::DeleteUIResource(UIResourceId uid) {
   }
 }
 
+void LayerTreeHostImpl::DeleteAllUIResources() {
+  for (UIResourceMap::const_iterator iter = ui_resource_map_.begin();
+      iter != ui_resource_map_.end();
+      ++iter) {
+    resource_provider_->DeleteResource(iter->second);
+  }
+  ui_resource_map_.clear();
+}
+
 ResourceProvider::ResourceId LayerTreeHostImpl::ResourceIdForUIResource(
     UIResourceId uid) const {
   UIResourceMap::const_iterator iter = ui_resource_map_.find(uid);