Reintroduce password support to NativeTextfieldViews

ui/views/controls/textfield/textfield_views_model.cc

Index: ui/views/controls/textfield/textfield_views_model.cc
diff --git a/ui/views/controls/textfield/textfield_views_model.cc b/ui/views/controls/textfield/textfield_views_model.cc
index d0fc8e01aec4c841e6429b8b3b7241661718158a..5b2cdaa41f2784c0452aa34b31438d7516df9c3e 100644
--- a/ui/views/controls/textfield/textfield_views_model.cc
+++ b/ui/views/controls/textfield/textfield_views_model.cc
@@ -9,6 +9,7 @@
 #include "base/i18n/break_iterator.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
+#include "base/utf_offset_string_conversions.h"
 #include "base/utf_string_conversions.h"
 #include "ui/base/clipboard/clipboard.h"
 #include "ui/base/clipboard/scoped_clipboard_writer.h"
@@ -361,9 +362,10 @@ bool TextfieldViewsModel::Backspace() {
     DeleteSelection();
     return true;
   }
-  if (GetCursorPosition() > 0) {
-    size_t cursor_position = GetCursorPosition();
-    ExecuteAndRecordDelete(cursor_position, cursor_position - 1, true);
+  size_t cursor_position = GetCursorPosition();
+  if (cursor_position > 0) {
+    size_t previous_char = Utf16OffsetToIndex(GetText(), cursor_position, -1);
+    ExecuteAndRecordDelete(cursor_position, previous_char, true);
     return true;
   }
   return false;
@@ -498,7 +500,7 @@ bool TextfieldViewsModel::Redo() {
 }
 
 bool TextfieldViewsModel::Cut() {
-  if (!HasCompositionText() && HasSelection()) {
+  if (!HasCompositionText() && HasSelection() && !render_text_->is_obscured()) {
     ui::ScopedClipboardWriter(views::ViewsDelegate::views_delegate
         ->GetClipboard()).WriteText(GetSelectedText());
     // A trick to let undo/redo handle cursor correctly.
@@ -515,7 +517,7 @@ bool TextfieldViewsModel::Cut() {
 }
 
 bool TextfieldViewsModel::Copy() {
-  if (!HasCompositionText() && HasSelection()) {
+  if (!HasCompositionText() && HasSelection() && !render_text_->is_obscured()) {
     ui::ScopedClipboardWriter(views::ViewsDelegate::views_delegate
         ->GetClipboard()).WriteText(GetSelectedText());
     return true;