make media gallery directory tooltips in media gallery config dialog absolute paths

chrome/browser/media_gallery/media_galleries_preferences.cc

Index: chrome/browser/media_gallery/media_galleries_preferences.cc
diff --git a/chrome/browser/media_gallery/media_galleries_preferences.cc b/chrome/browser/media_gallery/media_galleries_preferences.cc
index 37434199a3b63ae0e27c914c461b0a41a6ff98a5..9c1eed68b2ec8b7d7a8de190d778c5ea6e2648fe 100644
--- a/chrome/browser/media_gallery/media_galleries_preferences.cc
+++ b/chrome/browser/media_gallery/media_galleries_preferences.cc
@@ -124,6 +124,11 @@ MediaGalleryPrefInfo::MediaGalleryPrefInfo()
 }
 MediaGalleryPrefInfo::~MediaGalleryPrefInfo() {}
 
+FilePath MediaGalleryPrefInfo::AbsolutePath() const {
+  FilePath base_path = MediaStorageUtil::FindDevicePathById(device_id);
+  return base_path.Append(path);
+}
+
 MediaGalleriesPreferences::MediaGalleriesPreferences(Profile* profile)
     : profile_(profile) {
   // Populate the default galleries if this is a fresh profile.