Reland of Call dispatcher's releaseRegistration when done with registrations

public/platform/modules/background_sync/WebSyncProvider.h

Index: public/platform/modules/background_sync/WebSyncProvider.h
diff --git a/public/platform/modules/background_sync/WebSyncProvider.h b/public/platform/modules/background_sync/WebSyncProvider.h
index 93a6d6943997912adbcfe5dd1fcc88364df769ef..36132b1a89730f8040a475ee81c0ffcbd18772e7 100644
--- a/public/platform/modules/background_sync/WebSyncProvider.h
+++ b/public/platform/modules/background_sync/WebSyncProvider.h
@@ -54,6 +54,19 @@ public:
         callbacks->onError(new WebSyncError(WebSyncError::ErrorTypeAbort, "Function not implemented."));
         delete callbacks;
     }
+
+    // Takes ownership of the WebServiceWorkerRegistration.
+    virtual void trackRegistration(WebSyncRegistration* registration)
+    {
+        // TODO(jkarlin): After landing both legs of the releaseRegistration CLs, make this a pure virtual function.
+        return;
+    }
+
+    virtual void releaseRegistration(int64_t syncId)
+    {
+        // TODO(jkarlin): After landing both legs of the releaseRegistration CLs, make this a pure virtual function.
+        return;
+    }
 };
 
 } // namespace blink