Update media galleries scan results, even when zero.

chrome/browser/media_galleries/media_scan_manager.cc

 // 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.
 
 #include "chrome/browser/media_galleries/media_scan_manager.h"
 
 #include "base/file_util.h"
 #include "base/files/file_enumerator.h"
 #include "base/logging.h"
 #include "base/time/time.h"
@@ skipping 142 matching lines @@
   // Updating prefs while iterating them will invalidate the pointer, so
   // calculate the changes first and then apply them.
   std::map<MediaGalleryPrefId, MediaGalleryScanResult> to_update;
   for (MediaGalleriesPrefInfoMap::const_iterator it = known_galleries.begin();
        it != known_galleries.end();
        ++it) {
     const MediaGalleryPrefInfo& gallery = it->second;
     if (!gallery.IsBlackListedType()) {
       MediaGalleryScanResult file_counts =
           SumFilesUnderPath(gallery.AbsolutePath(), child_folders);
-      if (!IsEmptyScanResult(file_counts) && !gallery.IsBlackListedType()) {
+      if (gallery.audio_count != file_counts.audio_count ||
+          gallery.image_count != file_counts.image_count ||
+          gallery.video_count != file_counts.video_count) {
         to_update[it->first] = file_counts;
       }
     }
   }
 
   for (std::map<MediaGalleryPrefId,
                 MediaGalleryScanResult>::const_iterator it = to_update.begin();
        it != to_update.end();
        ++it) {
     const MediaGalleryPrefInfo& gallery =
@@ skipping 313 matching lines @@
                                                            gallery_count,
                                                            file_counts);
       }
     }
     scanning_extensions->clear();
     preferences->SetLastScanCompletionTime(base::Time::Now());
   }
   registrar_.RemoveAll();
   folder_finder_.reset();
 }