Prevent tabs sync during browser shutdown.

components/sync_sessions/sessions_sync_manager_unittest.cc

Index: components/sync_sessions/sessions_sync_manager_unittest.cc
diff --git a/components/sync_sessions/sessions_sync_manager_unittest.cc b/components/sync_sessions/sessions_sync_manager_unittest.cc
index ab5cbfde94db4bca324d1de09698e5347f57bed4..aa2de49d10cc62d1a369d0ddb66c179c4f3711c9 100644
--- a/components/sync_sessions/sessions_sync_manager_unittest.cc
+++ b/components/sync_sessions/sessions_sync_manager_unittest.cc
@@ -1760,6 +1760,30 @@ TEST_F(SessionsSyncManagerTest, OnLocalTabModified) {
   EXPECT_EQ(1, window->GetTabAt(1)->GetSyncId());
 }
 
+TEST_F(SessionsSyncManagerTest, TabSyncChangesOnShutdown) {
+  SyncChangeList out;
+  // Init with no local data, relies on MergeLocalSessionNoTabs.
+  TestSyncedWindowDelegate* window = AddWindow();
+  SessionID::id_type window_id = window->GetSessionId();
+  InitWithSyncDataTakeOutput(syncer::SyncDataList(), &out);
+  EXPECT_FALSE(manager()->current_machine_tag().empty());
+  EXPECT_EQ(2U, out.size());
+
+  NavigateTab(AddTab(window_id, kFoo1), kFoo2);
+  NavigateTab(AddTab(window_id, kBar1), kBar2);
+  out.clear();
+
+  EXPECT_FALSE(manager()->GetAllBrowsersClosingForTesting());
+  manager()->SetAllBrowsersClosing(true);
+  browser()->tab_strip_model()->CloseWebContentsAt(1,
+                                                   TabStripModel::CLOSE_NONE);
+  EXPECT_EQ(0U, out.size());
+
+  manager()->SetAllBrowsersClosing(false);
+  browser()->tab_strip_model()->CloseAllTabs();
+  EXPECT_EQ(1U, out.size());
+}
+
 TEST_F(SessionsSyncManagerTest, ForeignSessionModifiedTime) {
   SyncDataList foreign_data;
   base::Time newest_time = base::Time::Now() - base::TimeDelta::FromDays(1);