Media Galleries: Change the media gallery name to be a JSON value with the name and pref id.

chrome/browser/media_gallery/media_file_system_registry.h

Index: chrome/browser/media_gallery/media_file_system_registry.h
===================================================================
--- chrome/browser/media_gallery/media_file_system_registry.h	(revision 157149)
+++ chrome/browser/media_gallery/media_file_system_registry.h	(working copy)
@@ -42,9 +42,14 @@
 class ScopedMediaDeviceMapEntry;
 
 struct MediaFileSystemInfo {
-  string16 name;
+  MediaFileSystemInfo(const std::string& fs_name,
+                      const FilePath& fs_path,
+                      const std::string& filesystem_id);
+  MediaFileSystemInfo();
+
+  std::string name;  // JSON string, must not contain slashes.
+  FilePath path;
   std::string fsid;
-  FilePath path;
 };
 
 typedef base::Callback<void(const std::vector<MediaFileSystemInfo>&)>