add print to pdf for headless

headless/lib/browser/headless_devtools_manager_delegate.h

 // 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.
 
 #ifndef HEADLESS_LIB_BROWSER_HEADLESS_DEVTOOLS_MANAGER_DELEGATE_H_
 #define HEADLESS_LIB_BROWSER_HEADLESS_DEVTOOLS_MANAGER_DELEGATE_H_
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include "base/callback_forward.h"
 #include "base/memory/weak_ptr.h"
 #include "base/values.h"
 #include "content/public/browser/devtools_manager_delegate.h"
 
 namespace headless {
 class HeadlessBrowserImpl;
 
 class HeadlessDevToolsManagerDelegate
     : public content::DevToolsManagerDelegate {
  public:
   explicit HeadlessDevToolsManagerDelegate(
       base::WeakPtr<HeadlessBrowserImpl> browser);
   ~HeadlessDevToolsManagerDelegate() override;
 
   // DevToolsManagerDelegate implementation:
   base::DictionaryValue* HandleCommand(content::DevToolsAgentHost* agent_host,
                                        base::DictionaryValue* command) override;
+  bool HandleAsyncCommand(content::DevToolsAgentHost* agent_host,
+                          base::DictionaryValue* command,
+                          const CommandCallback& callback) override;
   scoped_refptr<content::DevToolsAgentHost> CreateNewTarget(
       const GURL& url) override;
   std::string GetDiscoveryPageHTML() override;
   std::string GetFrontendResource(const std::string& path) override;
 
  private:
   std::unique_ptr<base::DictionaryValue> CreateTarget(
       int command_id,
       const base::DictionaryValue* params);
   std::unique_ptr<base::DictionaryValue> CloseTarget(
       int command_id,
       const base::DictionaryValue* params);
   std::unique_ptr<base::DictionaryValue> CreateBrowserContext(
       int command_id,
       const base::DictionaryValue* params);
   std::unique_ptr<base::DictionaryValue> DisposeBrowserContext(
       int command_id,
       const base::DictionaryValue* params);
+  void PrintToPDF(content::DevToolsAgentHost* agent_host,
+                  int command_id,
+                  const base::DictionaryValue* params,
+                  const CommandCallback& callback);
 
   base::WeakPtr<HeadlessBrowserImpl> browser_;
 
   using CommandMemberCallback =
       base::Callback<std::unique_ptr<base::DictionaryValue>(
           int command_id,
           const base::DictionaryValue* params)>;
+  using AsyncCommandMemberCallback =
+      base::Callback<void(content::DevToolsAgentHost* agent_host,
+                          int command_id,
+                          const base::DictionaryValue* params,
+                          const CommandCallback& callback)>;
   std::map<std::string, CommandMemberCallback> command_map_;
+  std::map<std::string, AsyncCommandMemberCallback> async_command_map_;
 };
 
 }  // namespace headless
 
 #endif  // HEADLESS_LIB_BROWSER_HEADLESS_DEVTOOLS_MANAGER_DELEGATE_H_