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 "content/public/browser/devtools_manager_delegate.h"
-
 #include <map>
 #include <memory>
 #include <string>
 
 #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,
+                          CommandCallback callback) override;

[Lei Zhang, 2017/03/29 01:38:03]

Pass by const-ref. You need to fix
content/public/browser/devtools_manager_delegate.h (from r451947) as well.

[jzfeng, 2017/03/29 03:50:13]

Done. So whenever I want to pass a callback, it should be const-ref, right?

[Eric Seckler, 2017/03/29 11:21:19]

Yeah, usually :)

   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,
+                  CommandCallback callback);
 
   base::WeakPtr<HeadlessBrowserImpl> browser_;
 
   using CommandMemberFnPtr = std::unique_ptr<base::DictionaryValue> (
       HeadlessDevToolsManagerDelegate::*)(int command_id,
                                           const base::DictionaryValue* params);
 
   std::map<std::string, CommandMemberFnPtr> command_map_;
+
+  using AsyncCommandMemberFnPtr = void (HeadlessDevToolsManagerDelegate::*)(

[Lei Zhang, 2017/03/29 01:38:03]

I asked on https://codereview.chromium.org/2119063002 why we have
CommandMemberFnPtr instead of using just base::Callback. Let's see how that
conversation proceeds and adjust this accordingly.

[jzfeng, 2017/03/29 03:50:13]

Sounds good. Maybe Eric can also answer this question.

[Eric Seckler, 2017/03/29 11:21:19]

Yeah, sounds like you came to a conclusion in the discussion on the other patch.
Feel free to stick with these function pointers for now, but cleaning up later
sounds good.

+      content::DevToolsAgentHost* agent_host,
+      int command_id,
+      const base::DictionaryValue* params,
+      CommandCallback callback);
+
+  std::map<std::string, AsyncCommandMemberFnPtr> async_command_map_;
 };
 
 }  // namespace headless
 
 #endif  // HEADLESS_LIB_BROWSER_HEADLESS_DEVTOOLS_MANAGER_DELEGATE_H_