Fix a crash on showing sync setup dialog in guest mode.

Navigating directly to chrome://settings/syncSetup in guest mode is causing a DCHECK() failure, since the ProfileSyncService is NULL in the guest mode.

This patch adds a NULL check on ProfileSyncService to fix the crash
and also terminates the sync setup if the service is NULL.

BUG=370861

Review URL: https://codereview.chromium.org/277433003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269566 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/webui/sync_setup_handler.cc

@@ -729,8 +729,11 @@ void SyncSetupHandler::HandleConfigure(const base::ListValue* args) {
 }
 
 void SyncSetupHandler::HandleShowSetupUI(const base::ListValue* args) {
-  ProfileSyncService* service = GetSyncService();
-  DCHECK(service);
+  if (!GetSyncService()) {
+    DLOG(WARNING) << "Cannot display sync UI when sync is disabled";
+    CloseUI();
+    return;
+  }
 
   SigninManagerBase* signin =
       SigninManagerFactory::GetForProfile(GetProfile());

chrome/browser/ui/webui/sync_setup_handler.h

@@ -61,6 +61,7 @@ class SyncSetupHandler : public options::OptionsPageUIHandler,
   friend class SyncSetupHandlerTest;
   FRIEND_TEST_ALL_PREFIXES(SyncSetupHandlerTest,
                            DisplayConfigureWithBackendDisabledAndCancel);
+  FRIEND_TEST_ALL_PREFIXES(SyncSetupHandlerTest, HandleSetupUIWhenSyncDisabled);
   FRIEND_TEST_ALL_PREFIXES(SyncSetupHandlerTest, SelectCustomEncryption);
   FRIEND_TEST_ALL_PREFIXES(SyncSetupHandlerTest, ShowSyncSetupWhenNotSignedIn);
   FRIEND_TEST_ALL_PREFIXES(SyncSetupHandlerTest, SuccessfullySetPassphrase);

chrome/browser/ui/webui/sync_setup_handler_unittest.cc

@@ -442,6 +442,19 @@ TEST_F(SyncSetupHandlerTest, ShowSyncSetupWhenNotSignedIn) {
 }
 #endif  // !defined(OS_CHROMEOS)
 
+// Verifies that the sync setup is terminated correctly when the
+// sync is disabled.
+TEST_F(SyncSetupHandlerTest, HandleSetupUIWhenSyncDisabled) {
+  EXPECT_CALL(*mock_pss_, IsManaged()).WillRepeatedly(Return(true));
+  handler_->HandleShowSetupUI(NULL);
+
+  // Sync setup is closed when sync is disabled.
+  EXPECT_EQ(NULL,
+            LoginUIServiceFactory::GetForProfile(
+                profile_.get())->current_login_ui());
+  ASSERT_FALSE(handler_->is_configuring_sync());
+}
+
 // Verifies that the handler correctly handles a cancellation when
 // it is displaying the spinner to the user.
 TEST_F(SyncSetupHandlerTest, DisplayConfigureWithBackendDisabledAndCancel) {