Implement GPC opt-out flag (uplift to 1.58.x)

browser/about_flags.cc

@@ -861,6 +861,14 @@
           kOsWin | kOsLinux | kOsMac,                                          \
           FEATURE_VALUE_TYPE(features::kBraveCopyCleanLinkByDefault),          \
       },                                                                       \
+      {                                                                        \
+          "brave-global-privacy-control-enabled",                              \
+          "Enable Global Privacy Control",                                     \
+          "Enable the Sec-GPC request header and the "                         \
+          "navigator.globalPrivacyControl JS API",                             \
+          kOsAll,                                                              \
+          FEATURE_VALUE_TYPE(blink::features::kBraveGlobalPrivacyControl),     \
+      },                                                                       \
       {                                                                        \
           "https-by-default",                                                  \
           "Use HTTPS by Default",                                              \

browser/net/brave_request_handler.cc

@@ -35,6 +35,7 @@
 #include "extensions/common/constants.h"
 #include "net/base/features.h"
 #include "net/base/net_errors.h"
+#include "third_party/blink/public/common/features.h"
 
 #if BUILDFLAG(ENABLE_BRAVE_WEBTORRENT)
 #include "brave/browser/net/brave_torrent_redirect_network_delegate_helper.h"
@@ -100,9 +101,12 @@ void BraveRequestHandler::SetupCallbacks() {
       base::BindRepeating(brave::OnBeforeStartTransaction_SiteHacksWork);
   before_start_transaction_callbacks_.push_back(start_transaction_callback);
 
-  start_transaction_callback = base::BindRepeating(
-      brave::OnBeforeStartTransaction_GlobalPrivacyControlWork);
-  before_start_transaction_callbacks_.push_back(start_transaction_callback);
+  if (base::FeatureList::IsEnabled(
+          blink::features::kBraveGlobalPrivacyControl)) {
+    start_transaction_callback = base::BindRepeating(
+        brave::OnBeforeStartTransaction_GlobalPrivacyControlWork);
+    before_start_transaction_callbacks_.push_back(start_transaction_callback);
+  }
 
   start_transaction_callback =
       base::BindRepeating(brave::OnBeforeStartTransaction_BraveServiceKey);

browser/net/global_privacy_control_network_delegate_helper_browsertest.cc

@@ -3,6 +3,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+#include "base/feature_list.h"
 #include "base/path_service.h"
 #include "base/thread_annotations.h"
 #include "brave/components/constants/brave_paths.h"
@@ -15,6 +16,9 @@
 #include "net/dns/mock_host_resolver.h"
 #include "net/test/embedded_test_server/http_request.h"
 #include "third_party/abseil-cpp/absl/types/optional.h"
+#include "third_party/blink/public/common/features.h"
+
+using blink::features::kBraveGlobalPrivacyControl;
 
 enum class GPCHeaderResult {
   kOk,
@@ -149,3 +153,37 @@ IN_PROC_BROWSER_TEST_F(GlobalPrivacyControlNetworkDelegateBrowserTest,
   EXPECT_EQ(MessageServiceWorker(rfh, "hasGpc"), true);
   EXPECT_EQ(MessageServiceWorker(rfh, "checkGpc"), true);
 }
+
+class GlobalPrivacyControlFlagDisabledTest
+    : public GlobalPrivacyControlNetworkDelegateBrowserTest {
+ public:
+  GlobalPrivacyControlFlagDisabledTest() {
+    feature_list_.InitAndDisableFeature(kBraveGlobalPrivacyControl);
+  }
+
+ private:
+  base::test::ScopedFeatureList feature_list_;
+};
+
+// When kGlobalPrivacyControl is disabled, the Sec-GPC header shouldn't be sent.
+IN_PROC_BROWSER_TEST_F(GlobalPrivacyControlFlagDisabledTest, SecGPCHeaderNot1) {
+  const GURL target = https_server().GetURL("a.test", "/simple.html");
+  StartTracking();
+  ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), target));
+  EXPECT_EQ(header_result(), GPCHeaderResult::kNoHeader);
+}
+
+// When kGlobalPrivacyControl is disabled, the `navigator.globalPrivacyControl`
+// should not return true.
+IN_PROC_BROWSER_TEST_F(GlobalPrivacyControlFlagDisabledTest,
+                       NavigatorGlobalPrivacyAPI) {
+  const GURL target = https_server().GetURL("a.test", "/simple.html");
+  ASSERT_TRUE(ui_test_utils::NavigateToURL(browser(), target));
+
+  auto* rfh = browser()
+                  ->tab_strip_model()
+                  ->GetActiveWebContents()
+                  ->GetPrimaryMainFrame();
+
+  EXPECT_EQ(false, content::EvalJs(rfh, "navigator.globalPrivacyControl"));
+}

chromium_src/third_party/blink/common/features.cc

@@ -100,6 +100,11 @@ BASE_FEATURE(kBraveRoundTimeStamps,
              "BraveRoundTimeStamps",
              base::FEATURE_ENABLED_BY_DEFAULT);
 
+// Enables the Global Privacy Control header and navigator APIs.
+BASE_FEATURE(kBraveGlobalPrivacyControl,
+             "BraveGlobalPrivacyControl",
+             base::FEATURE_ENABLED_BY_DEFAULT);
+
 // Enable EventSource connection pool limit per eTLD+1.
 BASE_FEATURE(kRestrictEventSourcePool,
              "RestrictEventSourcePool",

chromium_src/third_party/blink/public/common/features.h

@@ -21,6 +21,7 @@ BLINK_COMMON_EXPORT BASE_DECLARE_FEATURE(kNavigatorConnectionAttribute);
 BLINK_COMMON_EXPORT BASE_DECLARE_FEATURE(kPartitionBlinkMemoryCache);
 BLINK_COMMON_EXPORT BASE_DECLARE_FEATURE(kRestrictWebSocketsPool);
 BLINK_COMMON_EXPORT BASE_DECLARE_FEATURE(kBraveBlockScreenFingerprinting);
+BLINK_COMMON_EXPORT BASE_DECLARE_FEATURE(kBraveGlobalPrivacyControl);
 BLINK_COMMON_EXPORT BASE_DECLARE_FEATURE(kBraveRoundTimeStamps);
 BLINK_COMMON_EXPORT BASE_DECLARE_FEATURE(kRestrictEventSourcePool);
 

third_party/blink/renderer/modules/global_privacy_control/global_privacy_control.cc

@@ -5,10 +5,13 @@
 
 #include "brave/third_party/blink/renderer/modules/global_privacy_control/global_privacy_control.h"
 
+#include "base/feature_list.h"
+#include "third_party/blink/public/common/features.h"
+
 namespace blink {
 
 bool GlobalPrivacyControl::globalPrivacyControl(NavigatorBase& navigator) {
-  return true;
+  return base::FeatureList::IsEnabled(features::kBraveGlobalPrivacyControl);
 }
 
 }  // namespace blink