message: [TF:TRT] Fix an uninitialized access.
  The third test that tests GetDeviceSet() returning nullptr actually accesses the
  uninitialized device_set_ field.
diff: @@ -71,7 +71,7 @@ class FakeCluster : public grappler::Cluster {
  }
  private:
  - const DeviceSet* device_set_;
  + const DeviceSet* device_set_ = nullptr;
  };
  TEST(ConvertGraphTest, GetDeviceAndAllocator) {
  