Magnifier: Prevent useless operation in enabling/disabling magnifier.

chrome/browser/chromeos/system/ash_system_tray_delegate.cc

Index: chrome/browser/chromeos/system/ash_system_tray_delegate.cc
diff --git a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
index 262cf9bc3418c9abdb9e110b5baac81402cd844d..e4411cefcc090561edf0da9e161330d0aaccc7a9 100644
--- a/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
+++ b/chrome/browser/chromeos/system/ash_system_tray_delegate.cc
@@ -32,6 +32,7 @@
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chromeos/accessibility/accessibility_util.h"
+#include "chrome/browser/chromeos/accessibility/magnification_manager.h"
 #include "chrome/browser/chromeos/audio/audio_handler.h"
 #include "chrome/browser/chromeos/cros/cros_library.h"
 #include "chrome/browser/chromeos/cros/network_library.h"
@@ -162,7 +163,8 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
                            public system::TimezoneSettings::Observer,
                            public device::BluetoothAdapter::Observer,
                            public SystemKeyEventListener::CapsLockObserver,
-                           public ash::NetworkTrayDelegate {
+                           public ash::NetworkTrayDelegate,
+                           public MagnificationObserver {
  public:
   SystemTrayDelegate()
       : ui_weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(
@@ -218,6 +220,8 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
     if (SystemKeyEventListener::GetInstance())
       SystemKeyEventListener::GetInstance()->AddCapsLockObserver(this);
 
+    MagnificationManager::GetInstance()->AddObserver(this);

[stevenjb, 2012/12/04 01:35:34]

We will need to ensure that we create MagnificationManager before this gets
called.

[yoshiki, 2012/12/04 08:30:20]

Done.

+
     spoken_feedback_enabled_.Init(
         prefs::kSpokenFeedbackEnabled,
         g_browser_process->local_state(),
@@ -253,6 +257,8 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
       SystemKeyEventListener::GetInstance()->RemoveCapsLockObserver(this);
     bluetooth_adapter_->RemoveObserver(this);
 
+    MagnificationManager::GetInstance()->RemoveObserver(this);

[stevenjb, 2012/12/04 01:35:34]

This can be:
if (MagnificationManager::GetInstance())
  MagnificationManager::GetInstance()->RemoveObserver(this)

That way shutdown order doesn't matter.

[yoshiki, 2012/12/04 08:30:20]

Done.

+
     // Stop observing gdata operations.
     DriveSystemService* system_service = FindDriveSystemService();
     if (system_service) {
@@ -778,10 +784,6 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
         prefs::kShowLogoutButtonInTray,
         base::Bind(&SystemTrayDelegate::UpdateShowLogoutButtonInTray,
                    base::Unretained(this)));
-    pref_registrar_->Add(
-        prefs::kMagnifierType,
-        base::Bind(&SystemTrayDelegate::OnAccessibilityModeChanged,
-                   base::Unretained(this)));
 
     UpdateClockType();
     UpdateShowLogoutButtonInTray();
@@ -1110,6 +1112,7 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
   }
 
   void OnAccessibilityModeChanged() {
+    LOG(ERROR) << "OnAccessibilityModeChanged";

[Daniel Erat, 2012/12/04 01:06:36]

nit: delete this

[yoshiki, 2012/12/04 08:30:20]

Done.

     GetSystemTrayNotifier()->NotifyAccessibilityModeChanged();
   }
 
@@ -1256,6 +1259,11 @@ class SystemTrayDelegate : public ash::SystemTrayDelegate,
     }
   }
 
+  // Overridden from MagnificationObserver
+  void OnMagnifierTypeChanged(ash::MagnifierType new_type) {
+    OnAccessibilityModeChanged();
+  }
+
   scoped_ptr<base::WeakPtrFactory<SystemTrayDelegate> > ui_weak_ptr_factory_;
   scoped_ptr<NetworkMenuIcon> network_icon_;
   scoped_ptr<NetworkMenuIcon> network_icon_dark_;