Sign user out before clearing data.

This also moves most of the logic out of ConfirmImportSyncDataDialog, leaving its callers to clear the data if requested.

BUG=597245

Review URL: https://codereview.chromium.org/1840303004

Cr-Commit-Position: refs/heads/master@{#384538}
diff --git a/chrome/android/java_sources.gni b/chrome/android/java_sources.gni
index 68ea00b..2eb05518 100644
--- a/chrome/android/java_sources.gni
+++ b/chrome/android/java_sources.gni
@@ -737,6 +737,7 @@
   "java/src/org/chromium/chrome/browser/sync/SyncController.java",
   "java/src/org/chromium/chrome/browser/sync/SyncNotificationController.java",
   "java/src/org/chromium/chrome/browser/sync/SyncSessionsMetrics.java",
+  "java/src/org/chromium/chrome/browser/sync/SyncUserDataWiper.java",
   "java/src/org/chromium/chrome/browser/sync/ui/ConfirmImportSyncDataDialog.java",
   "java/src/org/chromium/chrome/browser/sync/ui/PassphraseActivity.java",
   "java/src/org/chromium/chrome/browser/sync/ui/PassphraseCreationDialogFragment.java",