Fix threading issues in WebDataRequestManager.

components/webdata/common/web_database_backend.cc

Index: components/webdata/common/web_database_backend.cc
diff --git a/components/webdata/common/web_database_backend.cc b/components/webdata/common/web_database_backend.cc
index a4446061f91307de7084ab03a4376ef5f0adfad7..bf057accf0b74fb3cea76d4af21f3e79bf25d2b5 100644
--- a/components/webdata/common/web_database_backend.cc
+++ b/components/webdata/common/web_database_backend.cc
@@ -56,7 +56,7 @@ void WebDatabaseBackend::DBWriteTaskWrapper(
     return;
 
   ExecuteWriteTask(task);
-  request_manager_->RequestCompleted(std::move(request));
+  request_manager_->RequestCompleted(std::move(request), nullptr);
 }
 
 void WebDatabaseBackend::ExecuteWriteTask(
@@ -75,8 +75,8 @@ void WebDatabaseBackend::DBReadTaskWrapper(
   if (request->IsCancelled())
     return;
 
-  request->SetResult(ExecuteReadTask(task));
-  request_manager_->RequestCompleted(std::move(request));
+  std::unique_ptr<WDTypedResult> result = ExecuteReadTask(task);
+  request_manager_->RequestCompleted(std::move(request), std::move(result));
 }
 
 std::unique_ptr<WDTypedResult> WebDatabaseBackend::ExecuteReadTask(