Move SystemLogsSource class into new file

chrome/browser/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 3161 matching lines @@
       "feedback/system_logs/chrome_system_logs_fetcher.cc",
       "feedback/system_logs/chrome_system_logs_fetcher.h",
       "feedback/system_logs/log_sources/chrome_internal_log_source.cc",
       "feedback/system_logs/log_sources/chrome_internal_log_source.h",
       "feedback/system_logs/log_sources/crash_ids_source.cc",
       "feedback/system_logs/log_sources/crash_ids_source.h",
       "feedback/system_logs/log_sources/memory_details_log_source.cc",
       "feedback/system_logs/log_sources/memory_details_log_source.h",
       "feedback/system_logs/system_logs_fetcher.cc",
       "feedback/system_logs/system_logs_fetcher.h",
+      "feedback/system_logs/system_logs_source.cc",
+      "feedback/system_logs/system_logs_source.h",
       "first_run/first_run.cc",
       "first_run/first_run.h",
       "first_run/first_run_dialog.h",
       "first_run/first_run_internal.h",
       "first_run/first_run_internal_linux.cc",
       "first_run/first_run_internal_mac.mm",
       "first_run/first_run_internal_posix.cc",
       "first_run/first_run_internal_win.cc",
       "first_run/upgrade_util.h",
       "first_run/upgrade_util_mac.cc",
@@ skipping 1413 matching lines @@
       "//components/search_engines",
       "//rlz:rlz_lib",
     ]
   }
 }
 
 service_manifest("preferences_forwarder_manifest") {
   name = "preferences_forwarder"
   source = "prefs/forwarder_manifest.json"
 }