Re-introduce the partial magnifier

ash/shell/shell_delegate_impl.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 "ash/shell/shell_delegate_impl.h"
 
 #include "ash/caps_lock_delegate_stub.h"
 #include "ash/host/root_window_host_factory.h"
 #include "ash/shell/example_factory.h"
 #include "ash/shell/launcher_delegate_impl.h"
 #include "ash/shell/context_menu.h"
 #include "ash/shell/toplevel_window.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/stacking_controller.h"
 #include "ash/wm/window_util.h"
 #include "base/message_loop.h"
 #include "ui/aura/window.h"
 
 namespace ash {
 namespace shell {
 
 ShellDelegateImpl::ShellDelegateImpl()
     : watcher_(NULL),
       launcher_delegate_(NULL),
       locked_(false),
       spoken_feedback_enabled_(false),
       high_contrast_enabled_(false),
-      screen_magnifier_type_(MAGNIFIER_OFF) {
+      screen_magnifier_enabled_(false),
+      screen_magnifier_type_(kDefaultMagnifierType) {
 }
 
 ShellDelegateImpl::~ShellDelegateImpl() {
 }
 
 void ShellDelegateImpl::SetWatcher(WindowWatcher* watcher) {
   watcher_ = watcher;
   if (launcher_delegate_)
     launcher_delegate_->set_watcher(watcher);
 }
@@ skipping 88 matching lines @@
 }
 
 void ShellDelegateImpl::ToggleHighContrast() {
   high_contrast_enabled_ = !high_contrast_enabled_;
 }
 
 bool ShellDelegateImpl::IsHighContrastEnabled() const {
   return high_contrast_enabled_;
 }
 
-void ShellDelegateImpl::SetMagnifier(MagnifierType type) {
+void ShellDelegateImpl::SetMagnifierEnabled(bool enabled) {
+  screen_magnifier_enabled_ = enabled;
+}
+
+void ShellDelegateImpl::SetMagnifierType(MagnifierType type) {
   screen_magnifier_type_ = type;
 }
 
+bool ShellDelegateImpl::IsMagnifierEnabled() const {
+  return screen_magnifier_enabled_;
+}
+
 MagnifierType ShellDelegateImpl::GetMagnifierType() const {
   return screen_magnifier_type_;
 }
 
 bool ShellDelegateImpl::ShouldAlwaysShowAccessibilityMenu() const {
   return false;
 }
 
 app_list::AppListViewDelegate* ShellDelegateImpl::CreateAppListViewDelegate() {
   return ash::shell::CreateAppListViewDelegate();
@@ skipping 58 matching lines @@
 aura::client::StackingClient* ShellDelegateImpl::CreateStackingClient() {
   return new StackingController;
 }
 
 RootWindowHostFactory* ShellDelegateImpl::CreateRootWindowHostFactory() {
   return RootWindowHostFactory::Create();
 }
 
 }  // namespace shell
 }  // namespace ash