FlatDomTreeExtractor to enable & disable DOM domain

headless/public/util/flat_dom_tree_extractor_browsertest.cc

Index: headless/public/util/flat_dom_tree_extractor_browsertest.cc
diff --git a/headless/public/util/flat_dom_tree_extractor_browsertest.cc b/headless/public/util/flat_dom_tree_extractor_browsertest.cc
index dcb418d7be1e1564a1a23d96e410646d6366f23e..e897301cd3a9b3ebf1316261bd04ffe52f6a1dc3 100644
--- a/headless/public/util/flat_dom_tree_extractor_browsertest.cc
+++ b/headless/public/util/flat_dom_tree_extractor_browsertest.cc
@@ -55,7 +55,6 @@ class FlatDomTreeExtractorBrowserTest
 
     extractor_.reset(new FlatDomTreeExtractor(devtools_client_.get()));
 
-    devtools_client_->GetDOM()->Enable();
     std::vector<std::string> css_whitelist = {
         "color",       "display",      "font-style", "font-family",
         "margin-left", "margin-right", "margin-top", "margin-bottom"};
@@ -911,7 +910,6 @@ class FlatDomTreeExtractorBrowserTest
                                                                 << i;
     }
 
-    devtools_client_->GetDOM()->Disable();
     FinishAsynchronousTest();
   }