Enable virtual keyboard in overview mode

ash/virtual_keyboard_controller.cc

Index: ash/virtual_keyboard_controller.cc
diff --git a/ash/virtual_keyboard_controller.cc b/ash/virtual_keyboard_controller.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6bd535a2d45b0d629f22c9f087cfadf104dcb892
--- /dev/null
+++ b/ash/virtual_keyboard_controller.cc
@@ -0,0 +1,31 @@
+// 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 "ash/virtual_keyboard_controller.h"
+
+#include "ash/shell.h"
+#include "ui/keyboard/keyboard_util.h"
+
+namespace ash {
+
+VirtualKeyboardController::VirtualKeyboardController() {
+  Shell::GetInstance()->AddShellObserver(this);
+}
+
+VirtualKeyboardController::~VirtualKeyboardController() {
+  Shell::GetInstance()->RemoveShellObserver(this);
+}
+
+void VirtualKeyboardController::OnMaximizeModeStarted() {
+  keyboard::SetTouchKeyboardEnabled(true);
+  Shell::GetInstance()->CreateKeyboard();
+}
+
+void VirtualKeyboardController::OnMaximizeModeEnded() {
+  keyboard::SetTouchKeyboardEnabled(false);
+  if (!keyboard::IsKeyboardEnabled())
+    Shell::GetInstance()->DeactivateKeyboard();
+}
+
+}  // namespace ash