When the download folder does not exist, change the download folder to a user's "Downloads"

chrome/browser/download/download_prefs.cc

Index: chrome/browser/download/download_prefs.cc
diff --git a/chrome/browser/download/download_prefs.cc b/chrome/browser/download/download_prefs.cc
index e9e0b7681d696fe9685943a79cbe45a17994d675..ff08c0f4cf01e4949bd47040c03d4bb1ff39e449 100644
--- a/chrome/browser/download/download_prefs.cc
+++ b/chrome/browser/download/download_prefs.cc
@@ -60,18 +60,18 @@ void DownloadPrefs::RegisterUserPrefs(PrefService* prefs) {
                              SavePackage::SAVE_AS_COMPLETE_HTML,
                              PrefService::UNSYNCABLE_PREF);
 
-  // The default download path is userprofile\download.
-  const FilePath& default_download_path =
-      download_util::GetDefaultDownloadDirectory();
+  // The user's default "Downloads" folder.
+  FilePath default_download_dir =
+      download_util::GetDefaultDownloadDirectoryFromPathService();
   prefs->RegisterFilePathPref(prefs::kDownloadDefaultDirectory,
-                              default_download_path,
+                              default_download_dir,
                               PrefService::UNSYNCABLE_PREF);
 
 #if defined(OS_CHROMEOS)
   // Ensure that the download directory specified in the preferences exists.
   BrowserThread::PostTask(
       BrowserThread::FILE, FROM_HERE,
-      NewRunnableFunction(&file_util::CreateDirectory, default_download_path));
+      NewRunnableFunction(&file_util::CreateDirectory, default_download_dir));
 #endif  // defined(OS_CHROMEOS)
 
   // If the download path is dangerous we forcefully reset it. But if we do
@@ -82,7 +82,7 @@ void DownloadPrefs::RegisterUserPrefs(PrefService* prefs) {
         prefs::kDownloadDefaultDirectory);
     if (download_util::DownloadPathIsDangerous(current_download_dir)) {
       prefs->SetFilePath(prefs::kDownloadDefaultDirectory,
-                         default_download_path);
+                         default_download_dir);
     }
     prefs->SetBoolean(prefs::kDownloadDirUpgraded, true);
   }
@@ -135,6 +135,14 @@ void DownloadPrefs::ResetAutoOpen() {
   SaveAutoOpenState();
 }
 
+FilePath DownloadPrefs::GetDefaultDownloadDirectory() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  if (!override_default_download_dir_.empty())
+    return override_default_download_dir_;
+  return download_util::GetDefaultDownloadDirectoryFromPathService();
+}
+
 void DownloadPrefs::SaveAutoOpenState() {
   std::string extensions;
   for (AutoOpenSet::iterator it = auto_open_.begin();
@@ -153,6 +161,30 @@ void DownloadPrefs::SaveAutoOpenState() {
   prefs_->SetString(prefs::kDownloadExtensionsToOpen, extensions);
 }
 
+void DownloadPrefs::OverrideDefaultDownloadDirectory(
+    const FilePath& override_default_download_dir) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // Duplicate overriding is not allowed.
+  DCHECK(override_default_download_dir_.empty());
+
+  FilePath default_download_dir = GetDefaultDownloadDirectory();
+  if (*download_path_ == default_download_dir)
+    download_path_.SetValue(override_default_download_dir);
+
+  override_default_download_dir_ = override_default_download_dir;
+}
+
+void DownloadPrefs::UnOverrideDefaultDownloadDirectory() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  DCHECK(!override_default_download_dir_.empty());
+  override_default_download_dir_.clear();
+
+  FilePath default_download_dir = GetDefaultDownloadDirectory();
+  download_path_.SetValue(default_download_dir);
+}
+
 bool DownloadPrefs::AutoOpenCompareFunctor::operator()(
     const FilePath::StringType& a,
     const FilePath::StringType& b) const {