Media Galleries Partial Deprecation: Remove scan functionality.

chrome/browser/media_galleries/media_galleries_preferences.h

Index: chrome/browser/media_galleries/media_galleries_preferences.h
diff --git a/chrome/browser/media_galleries/media_galleries_preferences.h b/chrome/browser/media_galleries/media_galleries_preferences.h
index 12fe922492a768cde522e5626b2f5304254fb34c..2525a4b2ebc5fe5484ed52001bec4a584dacc618 100644
--- a/chrome/browser/media_galleries/media_galleries_preferences.h
+++ b/chrome/browser/media_galleries/media_galleries_preferences.h
@@ -270,11 +270,6 @@ class MediaGalleriesPreferences
 
   const MediaGalleriesPrefInfoMap& known_galleries() const;
 
-  // These keep track of when we last successfully completed a media scan.
-  // This is used to provide cached results when appropriate.
-  base::Time GetLastScanCompletionTime() const;
-  void SetLastScanCompletionTime(const base::Time& time);
-
   // KeyedService implementation:
   void Shutdown() override;