Re-introduce the partial magnifier

chrome/browser/chromeos/accessibility/magnification_manager.cc

Index: chrome/browser/chromeos/accessibility/magnification_manager.cc
diff --git a/chrome/browser/chromeos/accessibility/magnification_manager.cc b/chrome/browser/chromeos/accessibility/magnification_manager.cc
index c4a7f686513bc1b2609b7514ad726af560f4b2d1..dc09e8245db27a2c292f3cac7d7b022ac098a88f 100644
--- a/chrome/browser/chromeos/accessibility/magnification_manager.cc
+++ b/chrome/browser/chromeos/accessibility/magnification_manager.cc
@@ -34,7 +34,8 @@ class MagnificationManagerImpl : public MagnificationManager,
  public:
   MagnificationManagerImpl() : first_time_update_(true),
                                profile_(NULL),
-                               type_(ash::MAGNIFIER_OFF) {
+                               type_(ash::MAGNIFIER_DEFAULT),
+                               enabled_(false) {
     registrar_.Add(this,
                   chrome::NOTIFICATION_SESSION_STARTED,
                   content::NotificationService::AllSources());
@@ -51,29 +52,47 @@ class MagnificationManagerImpl : public MagnificationManager,
   }
 
   // MagnificationManager implimentation:
-  ash::MagnifierType GetMagnifierType() OVERRIDE {
+  bool IsMagnifierEnabled() const OVERRIDE {
+    return enabled_;
+  }
+
+  ash::MagnifierType GetMagnifierType() const OVERRIDE {
     return type_;
   }
 
-  void SetMagnifier(ash::MagnifierType type) OVERRIDE {
-    if (type == type_ && type == ash::MAGNIFIER_OFF)
+  void SetMagnifier(bool enabled, ash::MagnifierType type) OVERRIDE {
+    if (type == ash::MAGNIFIER_TYPE_UNCHANGE)
+      type = type_;
+
+    if (enabled_ == enabled && type_ == type && !enabled)
       return;
 
+    DCHECK(type == ash::MAGNIFIER_FULL || type == ash::MAGNIFIER_PARTIAL);
+
+    enabled_ = enabled;
     type_ = type;
 
     if (profile_) {
       PrefService* prefs = profile_->GetPrefs();
-      if (prefs) {
-        bool enabled = (type != ash::MAGNIFIER_OFF);
-        if (enabled != prefs->GetBoolean(prefs::kScreenMagnifierEnabled)) {
-          prefs->SetBoolean(prefs::kScreenMagnifierEnabled, enabled);
-          prefs->CommitPendingWrite();
-        }
+      DCHECK(prefs);
+      bool changed = false;
+
+      if (enabled != prefs->GetBoolean(prefs::kScreenMagnifierEnabled)) {
+        prefs->SetBoolean(prefs::kScreenMagnifierEnabled, enabled);
+        changed = true;
+      }
+
+      if (type != prefs->GetInteger(prefs::kScreenMagnifierType)) {
+        prefs->SetInteger(prefs::kScreenMagnifierType, type);
+        changed = true;
       }
+
+      if (changed)
+        prefs->CommitPendingWrite();
     }
 
     accessibility::AccessibilityStatusEventDetails details(
-        type != ash::MAGNIFIER_OFF, ash::A11Y_NOTIFICATION_NONE);
+        enabled, type, ash::A11Y_NOTIFICATION_NONE);
     content::NotificationService::current()->Notify(
         chrome::NOTIFICATION_CROS_ACCESSIBILITY_TOGGLE_SCREEN_MAGNIFIER,
         content::NotificationService::AllSources(),
@@ -81,34 +100,46 @@ class MagnificationManagerImpl : public MagnificationManager,
             &details));
 
     ash::Shell::GetInstance()->magnification_controller()->SetEnabled(
-        type == ash::MAGNIFIER_FULL);
+        enabled && type == ash::MAGNIFIER_FULL);
     ash::Shell::GetInstance()->partial_magnification_controller()->SetEnabled(
-        type == ash::MAGNIFIER_PARTIAL);
+        enabled && type == ash::MAGNIFIER_PARTIAL);
   }
 
   void SaveScreenMagnifierScale(double scale) OVERRIDE {
     Profile* profile = ProfileManager::GetDefaultProfileOrOffTheRecord();
+    DCHECK(profile->GetPrefs());
     profile->GetPrefs()->SetDouble(prefs::kScreenMagnifierScale, scale);
   }
 
-  double GetSavedScreenMagnifierScale() OVERRIDE {
+  double GetSavedScreenMagnifierScale() const OVERRIDE {
     Profile* profile = ProfileManager::GetDefaultProfileOrOffTheRecord();
+    DCHECK(profile->GetPrefs());
     if (profile->GetPrefs()->HasPrefPath(prefs::kScreenMagnifierScale))
       return profile->GetPrefs()->GetDouble(prefs::kScreenMagnifierScale);
     return std::numeric_limits<double>::min();
   }
 
  private:
+  bool IsMagnifierEnabledFromPref() {
+    if (!profile_)
+      return false;
+
+    DCHECK(profile_->GetPrefs());
+    return profile_->GetPrefs()->GetBoolean(prefs::kScreenMagnifierEnabled);
+  }
+
   ash::MagnifierType GetMagnifierTypeFromPref() {
     if (!profile_)
-      return ash::MAGNIFIER_OFF;
+      return ash::MAGNIFIER_DEFAULT;
 
-    PrefService* prefs = profile_->GetPrefs();
-    if (!prefs)
-      return ash::MAGNIFIER_OFF;
+    DCHECK(profile_->GetPrefs());
+    ash::MagnifierType type = static_cast<ash::MagnifierType>(
+        profile_->GetPrefs()->GetInteger(prefs::kScreenMagnifierType));
 
-    return prefs->GetBoolean(prefs::kScreenMagnifierEnabled) ?
-        ash::MAGNIFIER_FULL : ash::MAGNIFIER_OFF;
+    if (type == ash::MAGNIFIER_FULL || type == ash::MAGNIFIER_PARTIAL)
+      return type;
+
+    return ash::MAGNIFIER_DEFAULT;
   }
 
   void SetProfile(Profile* profile) {
@@ -123,6 +154,10 @@ class MagnificationManagerImpl : public MagnificationManager,
           prefs::kScreenMagnifierEnabled,
           base::Bind(&MagnificationManagerImpl::UpdateMagnifierStatus,
                      base::Unretained(this)));
+      pref_change_registrar_->Add(
+          prefs::kScreenMagnifierType,
+          base::Bind(&MagnificationManagerImpl::UpdateMagnifierStatus,
+                     base::Unretained(this)));
     }
 
     profile_ = profile;
@@ -130,8 +165,7 @@ class MagnificationManagerImpl : public MagnificationManager,
   }
 
   void UpdateMagnifierStatus() {
-    ash::MagnifierType type = GetMagnifierTypeFromPref();
-    SetMagnifier(type);
+    SetMagnifier(IsMagnifierEnabledFromPref(), GetMagnifierTypeFromPref());
   }
 
   // content::NotificationObserver implimentation:
@@ -155,6 +189,7 @@ class MagnificationManagerImpl : public MagnificationManager,
   bool first_time_update_;
   Profile* profile_;
   ash::MagnifierType type_;
+  bool enabled_;
   content::NotificationRegistrar registrar_;
   scoped_ptr<PrefChangeRegistrar> pref_change_registrar_;