message: Move GetDeviceStates() and GetNodeState() functions from protected to public, so that the user can have access to more detailed results from VirtualScheduler.
diff: @@ -275,7 +275,6 @@ class VirtualScheduler {
  // Return per device peak memory usage.
  const std::unordered_map<string, int64> GetPeakMemoryUsage() const;
  - protected:
  const std::unordered_map<string, DeviceState>* GetDeviceStates() const {
  return &device_;
  }
  @@ -283,6 +282,7 @@ class VirtualScheduler {
  return &node_map_;
  }
  + protected:
  // Returns the size of output at port_num (unit: bytes). A special case is
  // port_num -1, which is for control dependency and assumed to be 4 bytes.
  int64 CalculateOutputSize(
  