Improve views::Slider keyboard handling.

ui/views/controls/slider.cc

 // Copyright (c) 2012 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/slider.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 225 matching lines @@
 bool Slider::OnMouseDragged(const ui::MouseEvent& event) {
   MoveButtonTo(event.location());
   return true;
 }
 
 void Slider::OnMouseReleased(const ui::MouseEvent& event) {
   OnSliderDragEnded();
 }
 
 bool Slider::OnKeyPressed(const ui::KeyEvent& event) {
-  float new_value = value_;
-  if (event.key_code() == ui::VKEY_LEFT)
-    new_value -= keyboard_increment_;
-  else if (event.key_code() == ui::VKEY_RIGHT)
-    new_value += keyboard_increment_;
-  else
-    return false;
-  SetValueInternal(new_value, VALUE_CHANGED_BY_USER);
+  int direction = 1;
+  switch (event.key_code()) {
+    case ui::VKEY_LEFT:
+      direction = base::i18n::IsRTL() ? 1 : -1;
+      break;
+    case ui::VKEY_RIGHT:
+      direction = base::i18n::IsRTL() ? -1 : 1;
+      break;
+    case ui::VKEY_UP:
+      direction = 1;
+      break;
+    case ui::VKEY_DOWN:
+      direction = -1;
+      break;
+
+    default:
+      return false;
+  }
+  SetValueInternal(value_ + direction * keyboard_increment_,
+                   VALUE_CHANGED_BY_USER);
   return true;
 }
 
 void Slider::GetAccessibleNodeData(ui::AXNodeData* node_data) {
   node_data->role = ui::AX_ROLE_SLIDER;
   node_data->SetName(accessible_name_);
   node_data->SetValue(base::UTF8ToUTF16(
       base::StringPrintf("%d%%", static_cast<int>(value_ * 100 + 0.5))));
 }
 
@@ skipping 79 matching lines @@
       event->SetHandled();
       if (event->details().touch_points() <= 1)
         OnSliderDragEnded();
       break;
     default:
       break;
   }
 }
 
 }  // namespace views