Remove BlockThirdPartyCookies preference

The boolean BlockThirdPartyCookies preference was replaced by
CookieControlsMode enum. Existing settings were migrated since M83.
Since all usage of the preference has been removed, the preference
can be removed and existing settings cleared.

Bug: 1104836
Change-Id: Ie6e38b0a424981395c627459d684030ea84a58b7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2387805Reviewed-by: Balazs Engedy <engedy@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Christian Dullweber <dullweber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803844}

chrome/browser/prefs/browser_prefs.cc

@@ -566,6 +566,9 @@ const char kHashedAvailablePages[] = "previews.offline_helper.available_pages";
 // Deprecated 7/2020
 const char kObservedSessionTime[] = "profile.observed_session_time";
 
+// Deprecated 9/2020
+const char kBlockThirdPartyCookies[] = "profile.block_third_party_cookies";
+
 // Register local state used only for migration (clearing or moving to a new
 // key).
 void RegisterLocalStatePrefsForMigration(PrefRegistrySimple* registry) {
@@ -674,6 +677,8 @@ void RegisterProfilePrefsForMigration(
   registry->RegisterDictionaryPref(kHashedAvailablePages);
 
   registry->RegisterDictionaryPref(kObservedSessionTime);
+
+  registry->RegisterBooleanPref(kBlockThirdPartyCookies, false);
 }
 
 }  // namespace
@@ -1339,4 +1344,7 @@ void MigrateObsoleteProfilePrefs(Profile* profile) {
 
   // Added 7/2020
   profile_prefs->ClearPref(kObservedSessionTime);
+
+  // Added 9/2020
+  profile_prefs->ClearPref(kBlockThirdPartyCookies);
 }

components/content_settings/core/browser/cookie_settings.cc

@@ -60,9 +60,6 @@ void CookieSettings::GetCookieSettings(
 
 void CookieSettings::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
-  registry->RegisterBooleanPref(
-      prefs::kBlockThirdPartyCookies, false,
-      user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
   registry->RegisterIntegerPref(
       prefs::kCookieControlsMode,
       static_cast<int>(CookieControlsMode::kIncognitoOnly),
@@ -240,7 +237,9 @@ void CookieSettings::GetCookieSettingInternal(
 
 CookieSettings::~CookieSettings() = default;
 
-bool CookieSettings::IsCookieControlsEnabled() {
+bool CookieSettings::ShouldBlockThirdPartyCookiesInternal() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
 #if defined(OS_IOS)
   if (!base::FeatureList::IsEnabled(kImprovedCookieControls))
     return false;
@@ -274,8 +273,7 @@ void CookieSettings::OnContentSettingChanged(
 void CookieSettings::OnCookiePreferencesChanged() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
-  bool new_block_third_party_cookies =
-      IsCookieControlsEnabled();
+  bool new_block_third_party_cookies = ShouldBlockThirdPartyCookiesInternal();
 
   // Safe to read |block_third_party_cookies_| without locking here because the
   // only place that writes to it is this method and it will always be run on

components/content_settings/core/browser/cookie_settings.h

@@ -140,9 +140,6 @@ class CookieSettings : public CookieSettingsBase,
 
   void RemoveObserver(Observer* obs) { observers_.RemoveObserver(obs); }
 
-  // Returns true when the improved cookie control UI should be shown.
-  // TODO(dullweber): Fix grammar.
-  bool IsCookieControlsEnabled();
 
  private:
   ~CookieSettings() override;
@@ -173,6 +170,10 @@ class CookieSettings : public CookieSettingsBase,
 
   void OnCookiePreferencesChanged();
 
+  // Evaluate if third-party cookies are blocked. Should only be called
+  // when the preference changes to update the internal state.
+  bool ShouldBlockThirdPartyCookiesInternal();
+
   base::ThreadChecker thread_checker_;
   base::ObserverList<Observer> observers_;
   scoped_refptr<HostContentSettingsMap> host_content_settings_map_;

components/content_settings/core/common/pref_names.cc

@@ -6,10 +6,6 @@
 
 namespace prefs {
 
-// Boolean that is true if we should unconditionally block third-party cookies,
-// regardless of other content settings.
-const char kBlockThirdPartyCookies[] = "profile.block_third_party_cookies";
-
 // CookieControlsMode enum value that decides when the cookie controls UI is
 // enabled. This will block third-party cookies similar to
 // kBlockThirdPartyCookies but with a new UI.

components/content_settings/core/common/pref_names.h

@@ -13,9 +13,6 @@ namespace prefs {
 // some of these are generated by WebsiteSettingsInfo from content settings
 // names.
 
-// TODO(crbug.com/967668): Remove direct access to these preferences and
-// replace with CookieSettings::ShouldBlockThirdPartyCookies().
-extern const char kBlockThirdPartyCookies[];
 extern const char kCookieControlsMode[];
 
 extern const char kContentSettingsVersion[];