Allow customization of HttpPostProviderFactory via ProfileSyncService

sync/internal_api/public/http_post_provider_factory.h

Index: sync/internal_api/public/http_post_provider_factory.h
diff --git a/sync/internal_api/public/http_post_provider_factory.h b/sync/internal_api/public/http_post_provider_factory.h
index 93466514ffb09745b01ea4f1831fac79faeceb49..29aa3500681866fe0e35c8d72e7299d6e18b7b1d 100644
--- a/sync/internal_api/public/http_post_provider_factory.h
+++ b/sync/internal_api/public/http_post_provider_factory.h
@@ -11,6 +11,7 @@
 
 namespace syncer {
 
+class CancelationSignal;
 class HttpPostProviderInterface;
 
 // A factory to create HttpPostProviders to hide details about the
@@ -23,6 +24,9 @@ class SYNC_EXPORT HttpPostProviderFactory {
 
   virtual void Init(const std::string& user_agent) = 0;
 
+  virtual void RegisterCancelationSignal(
+      CancelationSignal* cancelation_signal) = 0;
+
   // Obtain a new HttpPostProviderInterface instance, owned by caller.
   virtual HttpPostProviderInterface* Create() = 0;