Add the UtilityProcessMojoClient class and convert SafeJsonParser

components/safe_json/safe_json_parser_impl.h

 // Copyright 2013 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 COMPONENTS_SAFE_JSON_SAFE_JSON_PARSER_IMPL_H_
 #define COMPONENTS_SAFE_JSON_SAFE_JSON_PARSER_IMPL_H_
 
 #include <memory>
 #include <string>
 
+#include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "components/safe_json/public/interfaces/safe_json.mojom.h"
 #include "components/safe_json/safe_json_parser.h"
-#include "content/public/browser/utility_process_host_client.h"
+#include "content/public/browser/utility_process_mojo_client.h"
 
 namespace base {
 class ListValue;
 class SequencedTaskRunner;
 class Value;
 }
 
-namespace content {
-class UtilityProcessHost;
-}
-
-namespace IPC {
-class Message;
-}
-
 namespace safe_json {
 
-class SafeJsonParserImpl : public content::UtilityProcessHostClient,
-                           public SafeJsonParser {
+class SafeJsonParserImpl : public SafeJsonParser {
  public:
   SafeJsonParserImpl(const std::string& unsafe_json,
                      const SuccessCallback& success_callback,
                      const ErrorCallback& error_callback);
 
  private:
   ~SafeJsonParserImpl() override;
 
-  void StartWorkOnIOThread();
-
-  void ReportResults();
-  void ReportResultsOnOriginThread();
-
-  // Implementing pieces of the UtilityProcessHostClient interface.
-  bool OnMessageReceived(const IPC::Message& message) override;
-
   // SafeJsonParser implementation.
   void Start() override;
 
+  void StartOnIOThread();
+  void OnConnectionError();
+
   // mojom::SafeJsonParser::Parse callback.
-  void OnParseDone(const base::ListValue& wrapper, mojo::String error);
+  void OnParseDone(const base::ListValue& wrapper, const mojo::String& error);
+
+  // Reports the result on the calling task runner via the |success_callback_|
+  // or the |error_callback_|.
+  void ReportResults(std::unique_ptr<base::Value> parsed_json,
+                     const std::string& error);
 
   const std::string unsafe_json_;
   SuccessCallback success_callback_;
   ErrorCallback error_callback_;
   scoped_refptr<base::SequencedTaskRunner> caller_task_runner_;
 
-  std::unique_ptr<base::Value> parsed_json_;
-  std::string error_;
+  std::unique_ptr<content::UtilityProcessMojoClient<mojom::SafeJsonParser>>
+      mojo_json_parser_;
 
-  base::WeakPtr<content::UtilityProcessHost> utility_process_host_;
-
-  mojom::SafeJsonParserPtr service_;
-
-  // To ensure the UtilityProcessHost and Mojo service are only accessed on the
-  // IO thread.
+  // Used instead of DCHECK_CURRENTLY_ON(BrowserThread::IO) because it's
+  // posssible that it fails when the IO thread message loop is shutting down.
+  // This happens after the IO thread has unregistered from the BrowserThread
+  // list.
   base::ThreadChecker io_thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(SafeJsonParserImpl);
 };
 
 }  // namespace safe_json
 
 #endif  // COMPONENTS_SAFE_JSON_SAFE_JSON_PARSER_IMPL_H_