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 38 matching lines @@
     parsed_window_size->set_width(width);
     parsed_window_size->set_height(height);
     return true;
   }
   return false;
 }
 }  // namespace
 
 // An application which implements a simple headless browser.
 class HeadlessShell : public HeadlessWebContents::Observer,
-                      emulation::ExperimentalObserver,
-                      inspector::ExperimentalObserver,
-                      page::Observer {
+                      public emulation::ExperimentalObserver,
+                      public inspector::ExperimentalObserver,
+                      public page::Observer {
  public:
   HeadlessShell()
       : browser_(nullptr),
         devtools_client_(HeadlessDevToolsClient::Create()),
         web_contents_(nullptr),
         processed_page_ready_(false),
         browser_context_(nullptr),
         weak_factory_(this) {}
   ~HeadlessShell() override {}
 
@@ skipping 178 matching lines @@
     } else if (base::CommandLine::ForCurrentProcess()->HasSwitch(
                    switches::kScreenshot)) {
       CaptureScreenshot();
     } else {
       Shutdown();
     }
   }
 
   void FetchDom() {
     devtools_client_->GetRuntime()->Evaluate(
-        "document.body.innerHTML",
+        "document.body.outerHTML",
         base::Bind(&HeadlessShell::OnDomFetched, weak_factory_.GetWeakPtr()));
   }
 
   void 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 239 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