Remove dead code that depends on protobuf support.

Change-Id: I9dc948f25f492af6d8de7987a32ba7afc20b81da

internal/ceres/linear_least_squares_problems.h

diff --git a/internal/ceres/linear_least_squares_problems.h b/internal/ceres/linear_least_squares_problems.h
index 0b550ff..fdeed70 100644
--- a/internal/ceres/linear_least_squares_problems.h
+++ b/internal/ceres/linear_least_squares_problems.h
@@ -63,8 +63,6 @@
 
 // Factories for linear least squares problem.
 LinearLeastSquaresProblem* CreateLinearLeastSquaresProblemFromId(int id);
-LinearLeastSquaresProblem* CreateLinearLeastSquaresProblemFromFile(
-    const string& filename);
 
 LinearLeastSquaresProblem* LinearLeastSquaresProblem0();
 LinearLeastSquaresProblem* LinearLeastSquaresProblem1();

internal/ceres/schur_eliminator_test.cc

diff --git a/internal/ceres/schur_eliminator_test.cc b/internal/ceres/schur_eliminator_test.cc
index 503a931..a7e96ae 100644
--- a/internal/ceres/schur_eliminator_test.cc
+++ b/internal/ceres/schur_eliminator_test.cc
@@ -59,13 +59,6 @@
     SetupHelper(problem.get());
   }
 
-  void SetUpFromFilename(const string& filename) {
-    scoped_ptr<LinearLeastSquaresProblem>
-        problem(CreateLinearLeastSquaresProblemFromFile(filename));
-    CHECK_NOTNULL(problem.get());
-    SetupHelper(problem.get());
-  }
-
   void SetupHelper(LinearLeastSquaresProblem* problem) {
     A.reset(down_cast<BlockSparseMatrix*>(problem->A.release()));
     b.reset(problem->b.release());