headless: Add a small C++ example application

headless/app/headless_shell.cc

 // Copyright 2016 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 <memory>
 #include <sstream>
 #include <string>
 
 #include "base/base64.h"
 #include "base/bind.h"
@@ skipping 243 matching lines @@
   } else if (base::CommandLine::ForCurrentProcess()->HasSwitch(
                  switches::kScreenshot)) {
     CaptureScreenshot();
   } else {
     Shutdown();
   }
 }
 
 void HeadlessShell::FetchDom() {
   devtools_client_->GetRuntime()->Evaluate(
-      "document.body.innerHTML",
+      "document.body.outerHTML",
       base::Bind(&HeadlessShell::OnDomFetched, weak_factory_.GetWeakPtr()));
 }
 
 void HeadlessShell::OnDomFetched(
     std::unique_ptr<runtime::EvaluateResult> result) {
   if (result->HasExceptionDetails()) {
-    LOG(ERROR) << "Failed to evaluate document.body.innerHTML: "
+    LOG(ERROR) << "Failed to evaluate document.body.outerHTML: "
                << result->GetExceptionDetails()->GetText();
   } else {
     std::string dom;
     if (result->GetResult()->GetValue()->GetAsString(&dom)) {
       printf("%s\n", dom.c_str());
     }
   }
   Shutdown();
 }
 
@@ skipping 228 matching lines @@
     builder.SetOverrideWebPreferencesCallback(base::Bind([](
         WebPreferences* preferences) { preferences->hide_scrollbars = true; }));
   }
 
   return HeadlessBrowserMain(
       builder.Build(),
       base::Bind(&HeadlessShell::OnStart, base::Unretained(&shell)));
 }
 
 }  // namespace headless