Move SystemLogsSource class into new file

chrome/browser/chromeos/system_logs/single_log_source.h

 // Copyright 2017 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 CHROME_BROWSER_CHROMEOS_SYSTEM_LOGS_SINGLE_LOG_SOURCE_H_
 #define CHROME_BROWSER_CHROMEOS_SYSTEM_LOGS_SINGLE_LOG_SOURCE_H_
 
 #include <stddef.h>
 #include <sys/types.h>
 
 #include "base/files/file.h"
 #include "base/macros.h"
-#include "chrome/browser/feedback/system_logs/system_logs_fetcher.h"
+#include "base/memory/weak_ptr.h"
+#include "chrome/browser/feedback/system_logs/system_logs_source.h"
 #include "components/feedback/anonymizer_tool.h"
 
 namespace base {
 class Time;
 }
 
 namespace system_logs {
 
 // Gathers log data from a single source, possibly incrementally.
 class SingleLogSource : public SystemLogsSource {
@@ skipping 61 matching lines @@
   feedback::AnonymizerTool anonymizer_;
 
   base::WeakPtrFactory<SingleLogSource> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SingleLogSource);
 };
 
 }  // namespace system_logs
 
 #endif  // CHROME_BROWSER_CHROMEOS_SYSTEM_LOGS_SINGLE_LOG_SOURCE_H_