Change linux default hidden file save directory to XDG_DATA_HOME

chrome/browser/download/chrome_download_manager_delegate.cc

 // Copyright (c) 2012 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/download/chrome_download_manager_delegate.h"
 
 #include <string>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 430 matching lines @@
 }
 
 void ChromeDownloadManagerDelegate::GetSaveDir(
     content::BrowserContext* browser_context,
     base::FilePath* website_save_dir,
     base::FilePath* download_save_dir,
     bool* skip_dir_check) {
   *website_save_dir = download_prefs_->SaveFilePath();
   DCHECK(!website_save_dir->empty());
   *download_save_dir = download_prefs_->DownloadPath();
+#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
+  // TODO(thomasanderson): Remove this when all Linux distros with
+  // versions of GTK lower than 3.14.7 are no longer supported.  This
+  // should happen when support for Ubuntu Trusty and Debian Jessie
+  // are removed.
+  //
+  // Use /var/tmp instead of /tmp here because /tmp may be
+  // memory-mounted and users may want to download files larger than
+  // will fit in memory.  Existence of /var/tmp is guaranteed by the
+  // Filesystem Hierarchy Standard.
+  static const char kVarTmp[] = "/var/tmp";
+  *download_save_dir = base::FilePath(kVarTmp);

[qinmin, 2017/06/06 22:10:14]

Shouldn't this be done in download_prefs_?
what if the *download_save_dir is defaulted to something else, either by test or
by user 

[Tom Anderson, 2017/06/07 01:29:51]

Done.

+#endif
   *skip_dir_check = false;
 #if defined(OS_CHROMEOS)
   *skip_dir_check = drive::util::IsUnderDriveMountPoint(*website_save_dir);
 #endif
 }
 
 void ChromeDownloadManagerDelegate::ChooseSavePath(
     content::WebContents* web_contents,
     const base::FilePath& suggested_path,
     const base::FilePath::StringType& default_extension,
@@ skipping 409 matching lines @@
       path.MatchesExtension(FILE_PATH_LITERAL(".xht")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".xhtm")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".xhtml")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".xsl")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".xslt"))) {
     return true;
   }
 #endif
   return false;
 }