Fix prefs registration for BrowserInstantController.

chrome/browser/ui/browser_instant_controller.cc

 // Copyright 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/ui/browser_instant_controller.h"
 
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/prefs/pref_registry_syncable.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 28 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // BrowserInstantController, public:
 
 BrowserInstantController::BrowserInstantController(Browser* browser)
     : browser_(browser),
       instant_(ALLOW_THIS_IN_INITIALIZER_LIST(this),
                chrome::search::IsInstantExtendedAPIEnabled(profile())),
       instant_unload_handler_(browser),
       initialized_theme_info_(false) {
-  profile_pref_registrar_.Init(profile()->GetPrefs());
+  PrefService* prefs = profile()->GetPrefs();
+
+  // kInstantExtendedEnabled takes the value of kInstantEnabled in this case.
+  if (search::GetInstantExtendedDefaultSetting() ==
+      search::INSTANT_USE_EXISTING) {
+    prefs->SetBoolean(prefs::kInstantExtendedEnabled,
+                      prefs->GetBoolean(prefs::kInstantEnabled));

[Mattias Nissler (ping if slow), 2013/02/22 13:06:16]

Note this is a change in semantics, not sure whether that's a good idea. I'd
rather change the code consuming kInstantExtendedEnabled to check for
IsDefaultValue() and if so, use the value of kInstantEnabled.

+  }
+
+  profile_pref_registrar_.Init(prefs);
   profile_pref_registrar_.Add(
       GetInstantPrefName(profile()),
       base::Bind(&BrowserInstantController::ResetInstant,
                  base::Unretained(this)));
   profile_pref_registrar_.Add(
       prefs::kSearchSuggestEnabled,
       base::Bind(&BrowserInstantController::ResetInstant,
                  base::Unretained(this)));
   ResetInstant();
   browser_->search_model()->AddObserver(this);
 
 #if defined(ENABLE_THEMES)
   // Listen for theme installation.
   registrar_.Add(this, chrome::NOTIFICATION_BROWSER_THEME_CHANGED,
                  content::Source<ThemeService>(
                      ThemeServiceFactory::GetForProfile(profile())));
 #endif  // defined(ENABLE_THEMES)
 }
 
 BrowserInstantController::~BrowserInstantController() {
   browser_->search_model()->RemoveObserver(this);
 }
 
 bool BrowserInstantController::IsInstantEnabled(Profile* profile) {
   return profile && !profile->IsOffTheRecord() && profile->GetPrefs() &&
          profile->GetPrefs()->GetBoolean(GetInstantPrefName(profile));
 }
 
 void BrowserInstantController::RegisterUserPrefs(
-    PrefService* prefs,
     PrefRegistrySyncable* registry) {
-  // TODO(joi): Get rid of the need for PrefService param above.
   registry->RegisterBooleanPref(prefs::kInstantConfirmDialogShown, false,
                                 PrefRegistrySyncable::SYNCABLE_PREF);
   registry->RegisterBooleanPref(prefs::kInstantEnabled, false,
                                 PrefRegistrySyncable::SYNCABLE_PREF);
 
   bool instant_extended_default = true;
   switch (search::GetInstantExtendedDefaultSetting()) {
     case search::INSTANT_DEFAULT_ON:
       instant_extended_default = true;
       break;
-    case search::INSTANT_USE_EXISTING:
-      instant_extended_default = prefs->GetBoolean(prefs::kInstantEnabled);
-      break;
+    case search::INSTANT_USE_EXISTING:  // Initialized in constructor.

[robertshield, 2013/02/22 13:36:55]

It took me a few minutes to convince myself that this would work since it wasn't
obvious to me that the default value passed to RegisterBooleanPref wouldn't be
used if prefs->SetBoolean was called in the ctor. 

Please expand the comment to say that "Initialized in constructor." means that
the default value passed to RegisterBooleanPref will be ignored.

     case search::INSTANT_DEFAULT_OFF:
       instant_extended_default = false;
       break;
   }
 
   registry->RegisterBooleanPref(prefs::kInstantExtendedEnabled,
                                 instant_extended_default,
                                 PrefRegistrySyncable::SYNCABLE_PREF);
 }
 
@@ skipping 235 matching lines @@
     initialized_theme_info_ = true;
   }
 
   DCHECK(initialized_theme_info_);
 
   if (browser_->search_model()->mode().is_ntp())
     instant_.ThemeChanged(theme_info_);
 }
 
 }  // namespace chrome