Magnifier: Change the login-screen default scale from 1.0x to 2.0x

chrome/browser/chromeos/accessibility/magnification_manager.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 "chrome/browser/chromeos/accessibility/magnification_manager.h"
 
 #include "ash/magnifier/magnification_controller.h"
 #include "ash/magnifier/partial_magnification_controller.h"
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_notifier.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
 #include "chrome/browser/api/prefs/pref_member.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/notification_service.h"
 
 namespace chromeos {
 
 namespace {
+const double kInitialMagnifiedScale = 2.0;
 static MagnificationManager* g_magnification_manager = NULL;
 }
 
 class MagnificationManagerImpl : public MagnificationManager,
                                  public content::NotificationObserver {
  public:
-  MagnificationManagerImpl() : profile_(NULL),
+  MagnificationManagerImpl() : first_time_update_(true),
+                               profile_(NULL),
                                type_(ash::MAGNIFIER_OFF) {
     registrar_.Add(this,
                   chrome::NOTIFICATION_SESSION_STARTED,
                   content::NotificationService::AllSources());
     registrar_.Add(this,
                   chrome::NOTIFICATION_PROFILE_DESTROYED,
                   content::NotificationService::AllSources());
     registrar_.Add(this,
                   chrome::NOTIFICATION_LOGIN_WEBUI_VISIBLE,
                   content::NotificationService::AllSources());
@@ skipping 84 matching lines @@
           prefs::kMagnifierType,
           base::Bind(&MagnificationManagerImpl::UpdateMagnifierStatus,
                      base::Unretained(this)));
     }
 
     profile_ = profile;
     UpdateMagnifierStatus();
   }
 
   void UpdateMagnifierStatus() {
+    // Historycally, from r162080 to r170956, screen magnifier had been enabled
+    // with 1.0x scale on login screen by default, hence some users
+    // unintentionally have the pref to enable magnifier. Now, the default scale
+    // is 2.0x on login screen (same as other screens), so despite them, with
+    // the old pref, their screen might be magnified with 2.0x scale.
+    // The following code prevents it. If the user on login screen has full
+    // screen magnifier pref but no scale pref, doesn't make magnifier enabled.

[Daniel Erat, 2012/12/06 15:15:47]

nit: can you add a TODO and/or bug to remove this in a release or two?

+    if (first_time_update_) {
+      first_time_update_ = false;
+      UserManager* manager = UserManager::Get();
+      if (profile_ &&
+          !profile_->GetPrefs()->HasPrefPath(prefs::kScreenMagnifierScale) &&
+          accessibility::MagnifierTypeFromName(profile_->GetPrefs()->GetString(
+              prefs::kMagnifierType).c_str()) == ash::MAGNIFIER_FULL &&
+          manager &&
+          !manager->IsSessionStarted()) {
+        SetMagnifier(ash::MAGNIFIER_OFF);
+        profile_->GetPrefs()->SetDouble(prefs::kScreenMagnifierScale,
+                                        kInitialMagnifiedScale);
+        return;
+      }
+    }
+
     ash::MagnifierType type = GetMagnifierTypeFromPref();
     SetMagnifier(type);
   }
 
   // content::NotificationObserver implimentation:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE {
     switch (type) {
       case chrome::NOTIFICATION_LOGIN_WEBUI_VISIBLE:
       case chrome::NOTIFICATION_SESSION_STARTED: {
         Profile* profile = ProfileManager::GetDefaultProfileOrOffTheRecord();
         SetProfile(profile);
         break;
       }
       case chrome::NOTIFICATION_PROFILE_DESTROYED: {
         SetProfile(NULL);
         break;
       }
     }
   }
 
+  bool first_time_update_;
   Profile* profile_;
   ash::MagnifierType type_;
   content::NotificationRegistrar registrar_;
   scoped_ptr<PrefChangeRegistrar> pref_change_registrar_;
 
   ObserverList<MagnificationObserver> observers_;
   DISALLOW_COPY_AND_ASSIGN(MagnificationManagerImpl);
 };
 
 // static
 void MagnificationManager::Initialize() {
   CHECK(g_magnification_manager == NULL);
   g_magnification_manager = new MagnificationManagerImpl();
 }
 
 // static
 void MagnificationManager::Shutdown() {
   CHECK(g_magnification_manager);
   delete g_magnification_manager;
   g_magnification_manager = NULL;
 }
 
 // static
 MagnificationManager* MagnificationManager::Get() {
   return g_magnification_manager;
 }
 
 }  // namespace chromeos