Win: Don't give some downloads duplicate extensions like .arj.arj

BUG=49621
TEST=See bug. Also unittests.

Review URL: http://codereview.chromium.org/3069018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@54625 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 29 insertions, 2 deletions

diff --git a/chrome/browser/views/shell_dialogs_win.cc b/chrome/browser/views/shell_dialogs_win.cc
index 7d74595..c1b6f5c 100644
--- a/chrome/browser/views/shell_dialogs_win.cc
+++ b/chrome/browser/views/shell_dialogs_win.cc
@@ -41,11 +41,14 @@ std::wstring AppendExtensionIfNeeded(const std::wstring& filename,
   DCHECK(!filename.empty());
   std::wstring return_value = filename;
 
-  // If the user didn't give us a known extension, and we wanted one, add it.
+  // If we wanted a specific extension, but the user's filename deleted it or
+  // changed it to something that the system doesn't understand, re-append.
   std::string selected_mime_type;
+  std::wstring file_extension = file_util::GetFileExtensionFromPath(filename);
   if (!(filter_selected.empty() || filter_selected == L"*.*") &&
       !net::GetMimeTypeFromExtension(
-          file_util::GetFileExtensionFromPath(filename), &selected_mime_type)) {
+          file_extension, &selected_mime_type) &&
+      file_extension != suggested_ext) {
     if (return_value[return_value.length() - 1] != L'.')
       return_value.append(L".");
     return_value.append(suggested_ext);
diff --git a/chrome/browser/views/shell_dialogs_win_unittest.cc b/chrome/browser/views/shell_dialogs_win_unittest.cc
index b267e16..bbe2525 100644
--- a/chrome/browser/views/shell_dialogs_win_unittest.cc
+++ b/chrome/browser/views/shell_dialogs_win_unittest.cc
@@ -70,3 +70,27 @@ TEST(AppendExtensionIfNeeded, AllFilesFilter_NoExtensionAppended) {
 
   ASSERT_EQ(L"sample.unknown-mime-type", actual_filename);
 }
+
+TEST(AppendExtensionIfNeeded, StripsDotsForUnknownSelectedMimeType) {
+  const std::wstring filename = L"product";
+  const std::wstring filter_selected = L"*.unknown-extension.";
+  const std::wstring suggested_ext = L"html";
+
+  const std::wstring actual_filename = AppendExtensionIfNeeded(filename,
+      filter_selected, suggested_ext);
+
+  ASSERT_EQ(L"product.html", actual_filename);
+}
+
+TEST(AppendExtensionIfNeeded, EqualToExtension_NoDoubleExtension) {
+  // Make sure we don't add a duplicate extension like .tbl.tbl for
+  // files that the system doesn't have a mime type for.
+  const std::wstring filename = L"product.tbl";
+  const std::wstring filter_selected = L"*.tbl";
+  const std::wstring suggested_ext = L"tbl";
+
+  const std::wstring actual_filename = AppendExtensionIfNeeded(filename,
+      filter_selected, suggested_ext);
+
+  ASSERT_EQ(L"product.tbl", actual_filename);
+}