Retry: sync: Gracefully handle early shutdown

sync/engine/net/server_connection_manager.h

Index: sync/engine/net/server_connection_manager.h
diff --git a/sync/engine/net/server_connection_manager.h b/sync/engine/net/server_connection_manager.h
index f9c4a544dfe62085c09dd0bdc9b0cb0ba95eb2e8..7496a5338b2fe9b97b12b33fcf6895e93801d230 100644
--- a/sync/engine/net/server_connection_manager.h
+++ b/sync/engine/net/server_connection_manager.h
@@ -16,6 +16,7 @@
 #include "base/threading/non_thread_safe.h"
 #include "base/threading/thread_checker.h"
 #include "sync/base/sync_export.h"
+#include "sync/internal_api/public/base/cancelation_observer.h"
 #include "sync/syncable/syncable_id.h"
 
 namespace sync_pb {
@@ -24,6 +25,8 @@ class ClientToServerMessage;
 
 namespace syncer {
 
+class CancelationSignal;
+
 namespace syncable {
 class Directory;
 }
@@ -125,7 +128,7 @@ class SYNC_EXPORT_PRIVATE ScopedServerStatusWatcher
 // Use this class to interact with the sync server.
 // The ServerConnectionManager currently supports POSTing protocol buffers.
 //
-class SYNC_EXPORT_PRIVATE ServerConnectionManager {
+class SYNC_EXPORT_PRIVATE ServerConnectionManager : public CancelationObserver {
  public:
   // buffer_in - will be POSTed
   // buffer_out - string will be overwritten with response
@@ -183,7 +186,8 @@ class SYNC_EXPORT_PRIVATE ServerConnectionManager {
   ServerConnectionManager(const std::string& server,
                           int port,
                           bool use_ssl,
-                          bool use_oauth2_token);
+                          bool use_oauth2_token,
+                          CancelationSignal* cancelation_signal);
 
   virtual ~ServerConnectionManager();
 
@@ -219,7 +223,7 @@ class SYNC_EXPORT_PRIVATE ServerConnectionManager {
   // We expect this to get called on a different thread than the valid
   // ThreadChecker thread, as we want to kill any pending http traffic without
   // having to wait for the request to complete.
-  virtual void TerminateAllIO();
+  virtual void OnSignalReceived() OVERRIDE FINAL;
 
   void set_client_id(const std::string& client_id) {
     DCHECK(thread_checker_.CalledOnValidThread());
@@ -342,6 +346,9 @@ class SYNC_EXPORT_PRIVATE ServerConnectionManager {
 
   void NotifyStatusChanged();
 
+  CancelationSignal* const cancelation_signal_;
+  bool signal_handler_registered_;
+
   DISALLOW_COPY_AND_ASSIGN(ServerConnectionManager);
 };