FlatDomTreeExtractor to enable & disable DOM domain

headless/public/util/flat_dom_tree_extractor.cc

Index: headless/public/util/flat_dom_tree_extractor.cc
diff --git a/headless/public/util/flat_dom_tree_extractor.cc b/headless/public/util/flat_dom_tree_extractor.cc
index 97aaeed8ea06264e89a7791abba9bf910bca3aef..1ac9210aabc618e3711f7e57df61a034db828180 100644
--- a/headless/public/util/flat_dom_tree_extractor.cc
+++ b/headless/public/util/flat_dom_tree_extractor.cc
@@ -26,6 +26,7 @@ void FlatDomTreeExtractor::ExtractDomTree(
 
   callback_ = std::move(callback);
 
+  devtools_client_->GetDOM()->Enable();
   devtools_client_->GetDOM()->GetFlattenedDocument(
       dom::GetFlattenedDocumentParams::Builder()
           .SetDepth(-1)
@@ -62,6 +63,7 @@ void FlatDomTreeExtractor::MaybeExtractDomTree() {
     }
     ExtractLayoutTreeNodes();
     ExtractComputedStyles();
+    devtools_client_->GetDOM()->Disable();
 
     work_in_progress_ = false;