sync: Gracefully handle very early shutdown

sync/internal_api/syncapi_server_connection_manager.h

Index: sync/internal_api/syncapi_server_connection_manager.h
diff --git a/sync/internal_api/syncapi_server_connection_manager.h b/sync/internal_api/syncapi_server_connection_manager.h
index 74312b3d463041cb8da8fddd23a34ad569704d94..68ef36c8fd23357c05842f4503525dc65087f713 100644
--- a/sync/internal_api/syncapi_server_connection_manager.h
+++ b/sync/internal_api/syncapi_server_connection_manager.h
@@ -12,9 +12,11 @@
 #include "base/memory/scoped_ptr.h"
 #include "sync/base/sync_export.h"
 #include "sync/engine/net/server_connection_manager.h"
+#include "sync/internal_api/public/base/cancellation_signal.h"
 
 namespace syncer {
 
+class ConnectionDisconnectHandle;
 class HttpPostProviderFactory;
 class HttpPostProviderInterface;
 
@@ -55,13 +57,16 @@ class SYNC_EXPORT_PRIVATE SyncAPIServerConnectionManager
                                  int port,
                                  bool use_ssl,
                                  bool use_oauth2_token,
-                                 HttpPostProviderFactory* factory);
+                                 HttpPostProviderFactory* factory,
+                                 CancellationSignal* cancellation_signal);
   virtual ~SyncAPIServerConnectionManager();
 
   // ServerConnectionManager overrides.
   virtual Connection* MakeConnection() OVERRIDE;
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(
+      SyncAPIServerConnectionManagerTest, VeryEarlyAbortPost);
   FRIEND_TEST_ALL_PREFIXES(SyncAPIServerConnectionManagerTest, EarlyAbortPost);
   FRIEND_TEST_ALL_PREFIXES(SyncAPIServerConnectionManagerTest, AbortPost);