Refactor UpgradeDetector.

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index e1fde1a56992402c944c043e8739081c79d7ab0a..15793e6290384256f4b7fd1cc1b24cadf5cfb7fe 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -721,6 +721,8 @@
         'browser/chromeos/tab_closeable_state_watcher.h',
         'browser/chromeos/update_observer.cc',
         'browser/chromeos/update_observer.h',
+        'browser/chromeos/upgrade_detector_chromeos.cc',
+        'browser/chromeos/upgrade_detector_chromeos.h',
         'browser/chromeos/user_cros_settings_provider.cc',
         'browser/chromeos/user_cros_settings_provider.h',
         'browser/chromeos/version_loader.cc',
@@ -3511,6 +3513,8 @@
         'browser/ui/window_snapshot/window_snapshot_x.cc',
         'browser/upgrade_detector.cc',
         'browser/upgrade_detector.h',
+        'browser/upgrade_detector_impl.cc',
+        'browser/upgrade_detector_impl.h',
         'browser/user_style_sheet_watcher.cc',
         'browser/user_style_sheet_watcher.h',
         'browser/visitedlink/visitedlink_event_listener.cc',
@@ -3627,6 +3631,8 @@
             'browser/password_manager/native_backend_kwallet_x.cc',
             'browser/password_manager/native_backend_kwallet_x.h',
             'browser/platform_util_linux.cc',
+            'browser/upgrade_detector_impl.cc',
+            'browser/upgrade_detector_impl.h',
           ],
         }],
         ['use_cups==1', {