Don't save last used locations in open and save dialogs when in incognito mode.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 4c64cf5a8bc153422f3df90762e99f34fd0e1c9a..39e5a71de89ddc37f3bc69f467198f6e4ca73beb 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -652,6 +652,10 @@ const wchar_t kDownloadDirUpgraded[] = L"download.directory_upgrade";
 // String which specifies where to save html files to by default.
 const wchar_t kSaveFileDefaultDirectory[] = L"savefile.default_directory";
 
+// String which specifies the last directory that was chosen for uploading
+// or opening a file.
+extern const wchar_t kSelectFileLastDirectory[] = L"selectfile.last_directory";
+
 // Extensions which should be opened upon completion.
 const wchar_t kDownloadExtensionsToOpen[] = L"download.extensions_to_open";