Add a TrustRegionStrategy::Summary object.

Change-Id: I7caee35a3408ee4a0ec16ba407410d822929340d
diff --git a/internal/ceres/levenberg_marquardt_strategy.h b/internal/ceres/levenberg_marquardt_strategy.h
index 4ed1390..90c2178 100644
--- a/internal/ceres/levenberg_marquardt_strategy.h
+++ b/internal/ceres/levenberg_marquardt_strategy.h
@@ -31,7 +31,7 @@
 #ifndef CERES_INTERNAL_LEVENBERG_MARQUARDT_STRATEGY_H_
 #define CERES_INTERNAL_LEVENBERG_MARQUARDT_STRATEGY_H_
 
-#include "ceres/linear_solver.h"
+#include "ceres/internal/eigen.h"
 #include "ceres/trust_region_strategy.h"
 
 namespace ceres {
@@ -48,7 +48,7 @@
   virtual ~LevenbergMarquardtStrategy();
 
   // TrustRegionStrategy interface
-  virtual LinearSolver::Summary ComputeStep(
+  virtual TrustRegionStrategy::Summary ComputeStep(
       const TrustRegionStrategy::PerSolveOptions& per_solve_options,
       SparseMatrix* jacobian,
       const double* residuals,