FlatDomTreeExtractor to enable & disable DOM domain

headless/public/util/flat_dom_tree_extractor_browsertest.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "headless/public/util/flat_dom_tree_extractor.h"
 
 #include <memory>
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/strings/string_util.h"
@@ skipping 37 matching lines @@
     devtools_client_->GetPage()->Navigate(
         embedded_test_server()->GetURL("/dom_tree_test.html").spec());
   }
 
   void OnLoadEventFired(const page::LoadEventFiredParams& params) override {
     devtools_client_->GetPage()->Disable();
     devtools_client_->GetPage()->RemoveObserver(this);
 
     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"};
     extractor_->ExtractDomTree(
         css_whitelist,
         base::Bind(&FlatDomTreeExtractorBrowserTest::OnDomTreeExtracted,
                    base::Unretained(this)));
   }
 
   void OnDomTreeExtracted(FlatDomTreeExtractor::DomTree dom_tree) {
@@ skipping 835 matching lines @@
       std::string result_json;
       base::JSONWriter::WriteWithOptions(*computed_styles[i],
                                          base::JSONWriter::OPTIONS_PRETTY_PRINT,
                                          &result_json);
 
       ASSERT_LT(i, expected_styles.size());
       EXPECT_EQ(NormaliseJSON(expected_styles[i]), result_json) << " Style # "
                                                                 << i;
     }
 
-    devtools_client_->GetDOM()->Disable();
     FinishAsynchronousTest();
   }
 
   std::unique_ptr<FlatDomTreeExtractor> extractor_;
 };
 
 HEADLESS_ASYNC_DEVTOOLED_TEST_F(FlatDomTreeExtractorBrowserTest);
 
 }  // namespace headless