Add group policy for sync service URL

browser/policy/brave_simple_policy_map.h

@@ -16,6 +16,7 @@
 
 #if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_MAC) || BUILDFLAG(IS_LINUX)
 #include "brave/components/brave_rewards/common/pref_names.h"
+#include "brave/components/brave_sync/brave_sync_prefs.h"
 #include "brave/components/brave_wallet/common/pref_names.h"
 #endif
 
@@ -43,7 +44,10 @@ inline constexpr PolicyToPreferenceMapEntry kBraveSimplePolicyMap[] = {
      kManagedBraveShieldsDisabledForUrls, base::Value::Type::LIST},
     {policy::key::kBraveShieldsEnabledForUrls,
      kManagedBraveShieldsEnabledForUrls, base::Value::Type::LIST},
+    {policy::key::kBraveSyncUrl, brave_sync::kCustomSyncServiceUrl,
+     base::Value::Type::STRING},
 #endif
+
 #if BUILDFLAG(ENABLE_TOR)
     {policy::key::kTorDisabled, tor::prefs::kTorDisabled,
      base::Value::Type::BOOLEAN},

chromium_src/components/policy/tools/generate_policy_source.py

@@ -166,6 +166,26 @@ def AddBravePolicies(template_file_contents):
             'desc': ('''This policy allows an admin to specify that Brave '''
                      '''AI Chat feature will be enabled.'''),
         },
+        {
+            'name': 'BraveSyncUrl',
+            'type': 'main',
+            'schema': {
+                'type': 'string'
+            },
+            'supported_on': ['chrome.*:129-'],
+            'features': {
+                'dynamic_refresh': False,
+                'per_profile': True,
+                'can_be_recommended': False,
+                'can_be_mandatory': True
+            },
+            'example_value': ['https://sync-v2.brave.com/v2'],
+            'id': 8,
+            'caption': '''Custom sync server URL.''',
+            'tags': [],
+            'desc': ('''This policy allows an admin to specify a custom '''
+                     '''sync server URL for Brave.'''),
+        },
     ]
 
     # Our new polices are added with highest id

chromium_src/components/sync/service/DEPS

@@ -1,3 +1,4 @@
 include_rules = [
+  "+brave/components/brave_sync",
   "+brave/components/sync/service",
 ]

chromium_src/components/sync/service/sync_service_impl.cc

@@ -3,13 +3,51 @@
  * 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 "brave/components/brave_sync/brave_sync_prefs.h"
 #include "brave/components/sync/service/brave_sync_auth_manager.h"
 #include "brave/components/sync/service/brave_sync_stopped_reporter.h"
+#include "components/prefs/pref_service.h"
+#include "components/sync/base/sync_util.h"
+
+namespace syncer {
+
+GURL BraveGetSyncServiceURL(const base::CommandLine& command_line,
+                            version_info::Channel channel,
+                            PrefService* prefs) {
+  // Allow group policy to override sync service URL.
+  // This has a higher priority than the --sync-url command-line param.
+  // https://github.com/brave/brave-browser/issues/20431
+  if (prefs && prefs->IsManagedPreference(brave_sync::kCustomSyncServiceUrl)) {
+    std::string value(prefs->GetString(brave_sync::kCustomSyncServiceUrl));
+    if (!value.empty()) {
+      GURL custom_sync_url(value);
+      // Provided URL must be HTTPS.
+      if (custom_sync_url.is_valid() &&
+          custom_sync_url.SchemeIs(url::kHttpsScheme)) {
+        DVLOG(2) << "Sync URL specified via GPO: "
+                 << prefs->GetString(brave_sync::kCustomSyncServiceUrl);
+        return custom_sync_url;
+      } else {
+        LOG(WARNING) << "The following sync URL specified via GPO "
+                     << "is invalid: " << value;
+      }
+    }
+  }
+
+  // Default logic.
+  // See `GetSyncServiceURL` in `components/sync/base/sync_util.cc`
+  return GetSyncServiceURL(command_line, channel);
+}
+
+}  // namespace syncer
 
 #define SyncAuthManager BraveSyncAuthManager
 #define SyncStoppedReporter BraveSyncStoppedReporter
+#define GetSyncServiceURL(...) \
+  BraveGetSyncServiceURL(__VA_ARGS__, sync_client_->GetPrefService())
 
 #include "src/components/sync/service/sync_service_impl.cc"
 
 #undef SyncAuthManager
 #undef SyncStoppedReporter
+#undef GetSyncServiceURL

components/brave_sync/brave_sync_prefs.cc

@@ -83,6 +83,7 @@ void Prefs::RegisterProfilePrefs(PrefRegistrySimple* registry) {
   registry->RegisterBooleanPref(kSyncFailedDecryptSeedNoticeDismissed, false);
   registry->RegisterBooleanPref(kSyncAccountDeletedNoticePending, false);
   registry->RegisterStringPref(kSyncLeaveChainDetails, std::string());
+  registry->RegisterStringPref(kCustomSyncServiceUrl, std::string());
 }
 
 // static

components/brave_sync/brave_sync_prefs.h

@@ -23,6 +23,8 @@ class Time;
 
 namespace brave_sync {
 
+inline constexpr char kCustomSyncServiceUrl[] = "brave_sync.sync_service_url";
+
 class Prefs {
  public:
   explicit Prefs(PrefService* pref_service);

components/sync/service/brave_sync_service_impl_unittest.cc

@@ -33,6 +33,7 @@
 #include "components/sync/test/fake_sync_manager.h"
 #include "components/sync/test/sync_service_impl_bundle.h"
 #include "components/sync/test/test_data_type_store_service.h"
+#include "components/sync_preferences/testing_pref_service_syncable.h"
 #include "content/public/test/browser_task_environment.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -126,7 +127,7 @@ class BraveSyncServiceImplTest : public testing::Test {
 
   SyncPrefs* sync_prefs() { return &sync_prefs_; }
 
-  PrefService* pref_service() {
+  sync_preferences::TestingPrefServiceSyncable* pref_service() {
     return sync_service_impl_bundle_.pref_service();
   }
 
@@ -155,6 +156,48 @@ class BraveSyncServiceImplTest : public testing::Test {
   std::unique_ptr<BraveSyncServiceImpl> sync_service_impl_;
 };
 
+TEST_F(BraveSyncServiceImplTest, GroupPolicyOverride) {
+  pref_service()->SetManagedPref(brave_sync::kCustomSyncServiceUrl,
+                                 base::Value("https://sync.example.com/v2"));
+
+  OSCryptMocker::SetUp();
+
+  CreateSyncService();
+
+  EXPECT_FALSE(engine());
+
+  GURL expected_service_url = GURL("https://sync.example.com/v2");
+  GURL actual_service_url =
+      brave_sync_service_impl()->GetSyncServiceUrlForDebugging();
+  EXPECT_EQ(expected_service_url, actual_service_url);
+
+  OSCryptMocker::TearDown();
+
+  pref_service()->SetManagedPref(brave_sync::kCustomSyncServiceUrl,
+                                 base::Value(""));
+}
+
+TEST_F(BraveSyncServiceImplTest, GroupPolicyNonHttpsOverride) {
+  pref_service()->SetManagedPref(brave_sync::kCustomSyncServiceUrl,
+                                 base::Value("http://sync.example.com/v2"));
+
+  OSCryptMocker::SetUp();
+
+  CreateSyncService();
+
+  EXPECT_FALSE(engine());
+
+  GURL expected_service_url = GURL("http://sync.example.com/v2");
+  GURL actual_service_url =
+      brave_sync_service_impl()->GetSyncServiceUrlForDebugging();
+  EXPECT_NE(expected_service_url, actual_service_url);
+
+  OSCryptMocker::TearDown();
+
+  pref_service()->SetManagedPref(brave_sync::kCustomSyncServiceUrl,
+                                 base::Value(""));
+}
+
 TEST_F(BraveSyncServiceImplTest, ValidPassphrase) {
   OSCryptMocker::SetUp();