Revert Implement "reduce language fingerprinting" and follow ups

app/brave_settings_strings.grdp

@@ -147,12 +147,6 @@
   <message name="IDS_SETTINGS_DE_AMP_SUB_LABEL" desc="The sub-label describing De-AMP feature">
     Always visit original (non-AMP) page URLs, instead of Google's Accelerated Mobile Page versions
   </message>
-  <message name="IDS_SETTINGS_BRAVE_SHIELDS_REDUCE_LANGUAGE_CONTROL_LABEL" desc="Default Brave reduce language control setting label">
-    Prevent sites from fingerprinting me based on my language preferences
-  </message>
-  <message name="IDS_SETTINGS_BRAVE_SHIELDS_REDUCE_LANGUAGE_SUBITEM" desc="Description that shows under main toggle setting for reduce language control setting label">
-    Enabling this setting reduces how much web sites can learn about your language preferences.
-  </message>
   <message name="IDS_SETTINGS_BRAVE_SHIELDS_AD_CONTROL_LABEL" desc="Default Brave block cross-site trackers control setting label">
     Trackers &amp; ads blocking
   </message>

browser/about_flags.cc

@@ -53,7 +53,6 @@ using brave_shields::features::kBraveDarkModeBlock;
 using brave_shields::features::kBraveDomainBlock;
 using brave_shields::features::kBraveDomainBlock1PES;
 using brave_shields::features::kBraveExtensionNetworkBlocking;
-using brave_shields::features::kBraveReduceLanguage;
 using brave_shields::features::kCosmeticFilteringSyncLoad;
 
 using de_amp::features::kBraveDeAMP;
@@ -140,10 +139,6 @@ constexpr char kBraveExtensionNetworkBlockingName[] =
 constexpr char kBraveExtensionNetworkBlockingDescription[] =
     "Enable blocking for network requests initiated by extensions";
 
-constexpr char kBraveReduceLanguageName[] = "Reduce language identifiability";
-constexpr char kBraveReduceLanguageDescription[] =
-    "Reduce the identifiability of my language preferences";
-
 constexpr char kCosmeticFilteringSyncLoadName[] =
     "Enable sync loading of cosmetic filter rules";
 constexpr char kCosmeticFilteringSyncLoadDescription[] =
@@ -517,10 +512,6 @@ const flags_ui::FeatureEntry::Choice kBraveSkusEnvChoices[] = {
      flag_descriptions::kBraveExtensionNetworkBlockingName,                 \
      flag_descriptions::kBraveExtensionNetworkBlockingDescription, kOsAll,  \
      FEATURE_VALUE_TYPE(kBraveExtensionNetworkBlocking)},                   \
-    {"brave-reduce-language",                                               \
-        flag_descriptions::kBraveReduceLanguageName,                        \
-        flag_descriptions::kBraveReduceLanguageDescription, kOsAll,         \
-        FEATURE_VALUE_TYPE(kBraveReduceLanguage)},                          \
     {"brave-cosmetic-filtering-sync-load",                                  \
      flag_descriptions::kCosmeticFilteringSyncLoadName,                     \
      flag_descriptions::kCosmeticFilteringSyncLoadDescription, kOsAll,      \

browser/brave_browser_process.h

@@ -21,7 +21,6 @@
 namespace brave {
 class BraveReferralsService;
 class BraveP3AService;
-class BraveFarblingService;
 }  // namespace brave
 
 namespace brave_component_updater {
@@ -105,7 +104,6 @@ class BraveBrowserProcess {
   speedreader_rewriter_service() = 0;
 #endif
   virtual brave_ads::ResourceComponent* resource_component() = 0;
-  virtual brave::BraveFarblingService* brave_farbling_service() = 0;
 };
 
 extern BraveBrowserProcess* g_brave_browser_process;

browser/brave_browser_process_impl.cc

@@ -5,7 +5,6 @@
 
 #include "brave/browser/brave_browser_process_impl.h"
 
-#include <string>
 #include <utility>
 
 #include "base/bind.h"
@@ -26,7 +25,6 @@
 #include "brave/components/brave_shields/browser/ad_block_regional_service_manager.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
 #include "brave/components/brave_shields/browser/ad_block_subscription_service_manager.h"
-#include "brave/components/brave_shields/browser/brave_farbling_service.h"
 #include "brave/components/brave_shields/browser/https_everywhere_service.h"
 #include "brave/components/brave_sync/network_time_helper.h"
 #include "brave/components/constants/pref_names.h"
@@ -48,7 +46,6 @@
 #include "content/public/browser/child_process_security_policy.h"
 #include "services/network/public/cpp/resource_request.h"
 #include "services/network/public/cpp/shared_url_loader_factory.h"
-#include "url/gurl.h"
 
 #if BUILDFLAG(ENABLE_BRAVE_REFERRALS)
 #include "brave/components/brave_referrals/browser/brave_referrals_service.h"
@@ -383,9 +380,3 @@ ipfs::BraveIpfsClientUpdater* BraveBrowserProcessImpl::ipfs_client_updater() {
   return ipfs_client_updater_.get();
 }
 #endif  // BUILDFLAG(ENABLE_IPFS)
-
-brave::BraveFarblingService* BraveBrowserProcessImpl::brave_farbling_service() {
-  if (!brave_farbling_service_)
-    brave_farbling_service_ = std::make_unique<brave::BraveFarblingService>();
-  return brave_farbling_service_.get();
-}

browser/brave_browser_process_impl.h

@@ -23,7 +23,6 @@ namespace brave {
 class BraveReferralsService;
 class BraveP3AService;
 class HistogramsBraveizer;
-class BraveFarblingService;
 }  // namespace brave
 
 namespace brave_component_updater {
@@ -116,7 +115,6 @@ class BraveBrowserProcessImpl : public BraveBrowserProcess,
   speedreader::SpeedreaderRewriterService* speedreader_rewriter_service()
       override;
 #endif
-  brave::BraveFarblingService* brave_farbling_service() override;
 
  private:
   // BrowserProcessImpl overrides:
@@ -175,8 +173,6 @@ class BraveBrowserProcessImpl : public BraveBrowserProcess,
       speedreader_rewriter_service_;
 #endif
 
-  std::unique_ptr<brave::BraveFarblingService> brave_farbling_service_;
-
   SEQUENCE_CHECKER(sequence_checker_);
 };
 

browser/brave_content_browser_client.cc

@@ -12,12 +12,12 @@
 
 #include "base/bind.h"
 #include "base/json/json_reader.h"
+#include "base/rand_util.h"
 #include "base/strings/strcat.h"
 #include "base/system/sys_info.h"
 #include "brave/browser/brave_browser_main_extra_parts.h"
 #include "brave/browser/brave_browser_process.h"
 #include "brave/browser/brave_shields/brave_shields_web_contents_observer.h"
-#include "brave/browser/brave_shields/reduce_language_navigation_throttle.h"
 #include "brave/browser/brave_wallet/brave_wallet_context_utils.h"
 #include "brave/browser/brave_wallet/brave_wallet_provider_delegate_impl.h"
 #include "brave/browser/brave_wallet/brave_wallet_service_factory.h"
@@ -44,7 +44,6 @@
 #include "brave/components/brave_search/common/brave_search_fallback.mojom.h"
 #include "brave/components/brave_search/common/brave_search_utils.h"
 #include "brave/components/brave_shields/browser/ad_block_service.h"
-#include "brave/components/brave_shields/browser/brave_farbling_service.h"
 #include "brave/components/brave_shields/browser/brave_shields_util.h"
 #include "brave/components/brave_shields/browser/domain_block_navigation_throttle.h"
 #include "brave/components/brave_shields/common/brave_shield_constants.h"
@@ -378,7 +377,9 @@ void MaybeBindSkusSdkImpl(
 
 }  // namespace
 
-BraveContentBrowserClient::BraveContentBrowserClient() {}
+BraveContentBrowserClient::BraveContentBrowserClient()
+    : session_token_(base::RandUint64()),
+      incognito_session_token_(base::RandUint64()) {}
 
 BraveContentBrowserClient::~BraveContentBrowserClient() {}
 
@@ -653,9 +654,11 @@ void BraveContentBrowserClient::AppendExtraCommandLineSwitches(
       Profile* profile =
           process ? Profile::FromBrowserContext(process->GetBrowserContext())
                   : nullptr;
-      session_token =
-          g_brave_browser_process->brave_farbling_service()->session_token(
-              profile && !profile->IsOffTheRecord());
+      if (profile && !profile->IsOffTheRecord()) {
+        session_token = session_token_;
+      } else {
+        session_token = incognito_session_token_;
+      }
     }
     command_line->AppendSwitchASCII("brave_session_token",
                                     base::NumberToString(session_token));
@@ -956,13 +959,6 @@ BraveContentBrowserClient::CreateThrottlesForNavigation(
               g_browser_process->GetApplicationLocale()))
     throttles.push_back(std::move(domain_block_navigation_throttle));
 
-  if (std::unique_ptr<content::NavigationThrottle>
-          reduce_language_navigation_throttle = brave_shields::
-              ReduceLanguageNavigationThrottle::MaybeCreateThrottleFor(
-                  handle, HostContentSettingsMapFactory::GetForProfile(
-                              Profile::FromBrowserContext(context))))
-    throttles.push_back(std::move(reduce_language_navigation_throttle));
-
   return throttles;
 }
 

browser/brave_content_browser_client.h

@@ -147,6 +147,9 @@ class BraveContentBrowserClient : public ChromeContentBrowserClient {
   blink::UserAgentMetadata GetUserAgentMetadata() override;
 
  private:
+  uint64_t session_token_;
+  uint64_t incognito_session_token_;
+
   void OnAllowGoogleAuthChanged();
 
   std::unique_ptr<PrefChangeRegistrar, content::BrowserThread::DeleteOnUIThread>

browser/brave_prefs_browsertest.cc

@@ -81,8 +81,6 @@ IN_PROC_BROWSER_TEST_F(BraveProfilePrefsBrowserTest, MiscBravePrefs) {
       brave_shields::prefs::kTwitterEmbedControlType));
   EXPECT_FALSE(chrome_test_utils::GetProfile(this)->GetPrefs()->GetBoolean(
       brave_shields::prefs::kLinkedInEmbedControlType));
-  EXPECT_TRUE(chrome_test_utils::GetProfile(this)->GetPrefs()->GetBoolean(
-      brave_shields::prefs::kReduceLanguageEnabled));
 #if BUILDFLAG(ENABLE_BRAVE_WAYBACK_MACHINE)
   EXPECT_TRUE(chrome_test_utils::GetProfile(this)->GetPrefs()->GetBoolean(
       kWebTorrentEnabled));

browser/brave_profile_prefs.cc

@@ -23,7 +23,6 @@
 #include "brave/components/brave_search/browser/brave_search_default_host.h"
 #include "brave/components/brave_search/common/brave_search_utils.h"
 #include "brave/components/brave_search_conversion/utils.h"
-#include "brave/components/brave_shields/browser/brave_farbling_service.h"
 #include "brave/components/brave_shields/browser/brave_shields_p3a.h"
 #include "brave/components/brave_shields/common/pref_names.h"
 #include "brave/components/brave_sync/brave_sync_prefs.h"
@@ -456,8 +455,6 @@ void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
       policy::policy_prefs::kIsolatedAppsDeveloperModeAllowed,
       base::Value(false));
 
-  BraveFarblingService::RegisterProfilePrefs(registry);
-
   RegisterProfilePrefsForMigration(registry);
 
 #if BUILDFLAG(ENABLE_BRAVE_TRANSLATE_GO)

browser/brave_shields/brave_shields_web_contents_observer.cc

@@ -15,13 +15,11 @@
 #include "brave/components/brave_shields/browser/brave_shields_util.h"
 #include "brave/components/brave_shields/common/brave_shield_constants.h"
 #include "brave/components/brave_shields/common/features.h"
-#include "brave/components/brave_shields/common/pref_names.h"
 #include "brave/components/constants/pref_names.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/renderer_configuration.mojom.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/pref_service.h"
-#include "components/user_prefs/user_prefs.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/navigation_handle.h"
 #include "content/public/browser/render_frame_host.h"
@@ -72,14 +70,6 @@ void BraveShieldsWebContentsObserver::RenderFrameCreated(RenderFrameHost* rfh) {
     GetBraveShieldsRemote(rfh)->SetAllowScriptsFromOriginsOnce(
         allowed_script_origins_);
   }
-  if (rfh) {
-    if (content::BrowserContext* context = rfh->GetBrowserContext()) {
-      if (PrefService* pref_service = user_prefs::UserPrefs::Get(context)) {
-        GetBraveShieldsRemote(rfh)->SetReduceLanguageEnabled(
-            brave_shields::IsReduceLanguageEnabledForProfile(pref_service));
-      }
-    }
-  }
 }
 
 void BraveShieldsWebContentsObserver::RenderFrameDeleted(RenderFrameHost* rfh) {
@@ -252,14 +242,6 @@ void BraveShieldsWebContentsObserver::ReadyToCommitNavigation(
             observer->GetBraveShieldsRemote(rfh)
                 ->SetAllowScriptsFromOriginsOnce(
                     observer->allowed_script_origins_);
-            if (content::BrowserContext* context = rfh->GetBrowserContext()) {
-              if (PrefService* pref_service =
-                      user_prefs::UserPrefs::Get(context)) {
-                observer->GetBraveShieldsRemote(rfh)->SetReduceLanguageEnabled(
-                    brave_shields::IsReduceLanguageEnabledForProfile(
-                        pref_service));
-              }
-            }
           },
           base::Unretained(this)));
 }