sync: Gracefully handle very early shutdown

sync/internal_api/sync_manager_impl.cc

Index: sync/internal_api/sync_manager_impl.cc
diff --git a/sync/internal_api/sync_manager_impl.cc b/sync/internal_api/sync_manager_impl.cc
index a541032691f0f7aa11aaa420185cc585d1a5b213..e8935dee8236408fb2c5d346fc23337c0bc91f1c 100644
--- a/sync/internal_api/sync_manager_impl.cc
+++ b/sync/internal_api/sync_manager_impl.cc
@@ -19,6 +19,7 @@
 #include "sync/engine/sync_scheduler.h"
 #include "sync/engine/syncer_types.h"
 #include "sync/internal_api/change_reorder_buffer.h"
+#include "sync/internal_api/public/base/cancellation_signal.h"
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/base/model_type_invalidation_map.h"
 #include "sync/internal_api/public/base_node.h"
@@ -355,12 +356,14 @@ void SyncManagerImpl::Init(
     Encryptor* encryptor,
     scoped_ptr<UnrecoverableErrorHandler> unrecoverable_error_handler,
     ReportUnrecoverableErrorFunction report_unrecoverable_error_function,
-    bool use_oauth2_token) {
+    bool use_oauth2_token,
+    CancellationSignal* cancellation_signal) {
   CHECK(!initialized_);
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(post_factory.get());
   DCHECK(!credentials.email.empty());
   DCHECK(!credentials.sync_token.empty());
+  DCHECK(cancellation_signal);
   DVLOG(1) << "SyncManager starting Init...";
 
   weak_handle_this_ = MakeWeakHandle(weak_ptr_factory_.GetWeakPtr());
@@ -420,7 +423,7 @@ void SyncManagerImpl::Init(
 
   connection_manager_.reset(new SyncAPIServerConnectionManager(
       sync_server_and_path, port, use_ssl, use_oauth2_token,
-      post_factory.release()));
+      post_factory.release(), cancellation_signal));
   connection_manager_->set_client_id(directory()->cache_guid());
   connection_manager_->AddListener(this);
 
@@ -448,7 +451,7 @@ void SyncManagerImpl::Init(
       invalidator_client_id).Pass();
   session_context_->set_account_name(credentials.email);
   scheduler_ = internal_components_factory->BuildScheduler(
-      name_, session_context_.get()).Pass();
+      name_, session_context_.get(), cancellation_signal).Pass();
 
   scheduler_->Start(SyncScheduler::CONFIGURATION_MODE);
 
@@ -619,13 +622,6 @@ void SyncManagerImpl::RemoveObserver(SyncManager::Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
-void SyncManagerImpl::StopSyncingForShutdown() {
-  DVLOG(2) << "StopSyncingForShutdown";
-  scheduler_->RequestStop();
-  if (connection_manager_)
-    connection_manager_->TerminateAllIO();
-}
-
 void SyncManagerImpl::ShutdownOnSyncThread() {
   DCHECK(thread_checker_.CalledOnValidThread());