Remove UMA.CreatePersistentHistogram.Result

This histogram isn't showing anything meaningful and the problems it
could show are better observed by looking at the allocators directly.

Bug: 831013
Change-Id: Ibe968597758230192e53a7675e7390e968c9e5b9
Reviewed-on: https://chromium-review.googlesource.com/1008047
Commit-Queue: Brian White <bcwhite@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549986}
bool GlobalHistogramAllocator::CreateWithActiveFileInDir(const FilePath& dir,
                                                         size_t size,
                                                         uint64_t id,
                                                         StringPiece name) {
  FilePath base_path, active_path, spare_path;
  ConstructFilePaths(dir, name, &base_path, &active_path, &spare_path);
  return CreateWithActiveFile(base_path, active_path, spare_path, size, id,
                              name);
}

bool GlobalHistogramAllocator::CreateWithActiveFileInDir(const FilePath& dir,
                                                         size_t size,
                                                         uint64_t id,
                                                         StringPiece name) {
  FilePath base_path, active_path, spare_path;
  ConstructFilePaths(dir, name, &base_path, &active_path, &spare_path);
  return CreateWithActiveFile(base_path, active_path, spare_path, size, id,
                              name);
}
