FileSystem: Modify ObfucatedFileUtil to delete contents of the plugin private filesystem

Database destruction functions haven't correctly worked for plugin private
filesystems since the filesystem has a different directory structure
from other filesystems as follows:

- PluginPrivate FS: /path/to/File System/Plugins/<origins>/<plugin_id>/<paths>/<file>
- Other FS: /path/to/File System/<origins>/<storage type>/<paths>/<file>

This patch tweaks those functions correctly to delete contents and
metadata of the plugin private filesystem.

NOTE: A part of tests is contributed by xhwang@chromium.org:
https://codereview.chromium.org/580363003/

BUG=326429
TEST=content_unittests --gtest_filter=PluginPrivateFileSystemBackendTest.*
TEST=content_unittests --gtest_filter=ObfuscatedFileUtilTest.*

Review URL: https://codereview.chromium.org/579083004

Cr-Commit-Position: refs/heads/master@{#303213}

1 files changed, 1 insertions, 1 deletions

diff --git a/storage/browser/fileapi/obfuscated_file_util.h b/storage/browser/fileapi/obfuscated_file_util.h
index d22d2e2..090e55e 100644
--- a/storage/browser/fileapi/obfuscated_file_util.h
+++ b/storage/browser/fileapi/obfuscated_file_util.h
@@ -197,7 +197,7 @@ class STORAGE_EXPORT_PRIVATE ObfuscatedFileUtil
 
   // Deletes a directory database from the database list in the ObfuscatedFSFU
   // and destroys the database on the disk.
-  bool DestroyDirectoryDatabase(const GURL& origin,
+  void DestroyDirectoryDatabase(const GURL& origin,
                                 const std::string& type_string);
 
   // Computes a cost for storing a given file in the obfuscated FSFU.