Delete blimp/helium and remove references to it from dependent targets

blimp/helium/revision_generator.cc

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "blimp/helium/revision_generator.h"
-
-namespace blimp {
-namespace helium {
-
-base::LazyInstance<RevisionGenerator> RevisionGenerator::instance_ =
-    LAZY_INSTANCE_INITIALIZER;
-
-const Revision& RevisionGenerator::GetNextRevision() {
-  DCHECK(sequence_checker_.CalledOnValidSequence())
-      << "GetNextRevision() must be called on the same sequenced thread.";
-  return ++revision_;
-}
-
-RevisionGenerator* RevisionGenerator::GetInstance() {
-  return instance_.Pointer();
-}
-
-Revision GetNextRevision() {
-  return RevisionGenerator::GetInstance()->GetNextRevision();
-}
-
-}  // namespace helium
-}  // namespace blimp