Ensure that text with leading, trailing and interspersed tabs pasted into the textfield

ui/views/controls/textfield/textfield_model.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/controls/textfield/textfield_model.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
 #include "ui/base/clipboard/clipboard.h"
 #include "ui/base/clipboard/scoped_clipboard_writer.h"
 #include "ui/gfx/range/range.h"
 #include "ui/gfx/utf16_indexing.h"
 
 namespace views {
 
 namespace internal {
 
 // Edit holds state information to undo/redo editing changes. Editing operations
@@ skipping 481 matching lines @@
 bool TextfieldModel::Copy() {
   if (!HasCompositionText() && HasSelection() && !render_text_->obscured()) {
     ui::ScopedClipboardWriter(
         ui::CLIPBOARD_TYPE_COPY_PASTE).WriteText(GetSelectedText());
     return true;
   }
   return false;
 }
 
 bool TextfieldModel::Paste() {
-  base::string16 result;
+  base::string16 text;
   ui::Clipboard::GetForCurrentThread()->ReadText(ui::CLIPBOARD_TYPE_COPY_PASTE,
-                                                 &result);
-  if (result.empty())
+                                                 &text);
+  if (text.empty())
     return false;
 
-  InsertTextInternal(result, false);
+  base::string16 actual_text = base::CollapseWhitespace(text, false);
+  // If the clipboard contains all whitespaces then paste a single space.
+  if (actual_text.empty())
+    actual_text = base::ASCIIToUTF16(" ");
+
+  InsertTextInternal(actual_text, false);
   return true;
 }
 
 bool TextfieldModel::HasSelection() const {
   return !render_text_->selection().is_empty();
 }
 
 void TextfieldModel::DeleteSelection() {
   DCHECK(!HasCompositionText());
   DCHECK(HasSelection());
@@ skipping 237 matching lines @@
   ClearComposition();
   if (delete_from != delete_to)
     render_text_->SetText(old_text.erase(delete_from, delete_to - delete_from));
   if (!new_text.empty())
     render_text_->SetText(old_text.insert(new_text_insert_at, new_text));
   render_text_->SetCursorPosition(new_cursor_pos);
   // TODO(oshima): Select text that was just undone, like Mac (but not GTK).
 }
 
 }  // namespace views