Update file extension based on the selected type in the save dialog.

ui/file_manager/file_manager/foreground/js/file_manager.js

Index: ui/file_manager/file_manager/foreground/js/file_manager.js
diff --git a/ui/file_manager/file_manager/foreground/js/file_manager.js b/ui/file_manager/file_manager/foreground/js/file_manager.js
index b1b9cbb2d1f830137cfc31907afaf5afb799a419..2a4920b7421f9b3552f53c360b45d587ac7f7a6f 100644
--- a/ui/file_manager/file_manager/foreground/js/file_manager.js
+++ b/ui/file_manager/file_manager/foreground/js/file_manager.js
@@ -1346,12 +1346,25 @@ var BOTTOM_MARGIN_FOR_PREVIEW_PANEL_PX = 52;
     this.fileFilter_.removeFilter('fileType');
     var selectedIndex = this.getSelectedFilterIndex_();
     if (selectedIndex > 0) { // Specific filter selected.
-      var regexp = new RegExp('.*(' +
+      var regexp = new RegExp('\\.(' +
           this.fileTypes_[selectedIndex - 1].extensions.join('|') + ')$', 'i');
       var filter = function(entry) {
         return entry.isDirectory || regexp.test(entry.name);
       };
       this.fileFilter_.addFilter('fileType', filter);
+
+      // In save dialog, update the destination name extension.
+      if (this.dialogType === DialogType.SELECT_SAVEAS_FILE) {
+        var current = this.filenameInput_.value;
+        var newExt = this.fileTypes_[selectedIndex - 1].extensions[0];
+        if (newExt && !regexp.test(current)) {

[hirono, 2014/06/11 07:14:05]

Maybe we can do just:
if (newExt) {
  this.filenameInput_.value = current.replace(regexp, '.' + newExt);
  this.selectTargetNameInFilenameInput_();
}

[kinaba, 2014/06/11 07:23:44]

Unfortunately not. |regexp| matches with the new extension,
while what we want to replace in |current| is the old extension
that did not match |regexp|.

+          var i = current.lastIndexOf('.');
+          if (i >= 0) {
+            this.filenameInput_.value = current.substr(0, i) + '.' + newExt;
+            this.selectTargetNameInFilenameInput_();
+          }
+        }
+      }
     }
   };