Polish code

test=develop

paddle/fluid/framework/grad_op_desc_maker.h

@@ -14,7 +14,9 @@ limitations under the License. */
 
 #pragma once
 #include <algorithm>
+#include <memory>
 #include <string>
+#include <unordered_map>
 #include <unordered_set>
 #include <vector>
 #include "paddle/fluid/framework/op_desc.h"

paddle/fluid/imperative/tracer.cc

@@ -131,8 +131,7 @@ framework::VariableNameMap CreateOutputVarNameMap(
   return result;
 }
 
-Tracer::Tracer(framework::BlockDesc* root_block) : root_block_(root_block) {
-}
+Tracer::Tracer(framework::BlockDesc* root_block) : root_block_(root_block) {}
 
 std::set<std::string> Tracer::Trace(OpBase* op, const VarBasePtrMap& inputs,
                                     const VarBasePtrMap& outputs,