precache: Extract common methods for PrecacheManifest into util.

components/precache/core/precache_manifest_util.cc

+// Copyright 2017 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 "components/precache/core/precache_manifest_util.h"
+
+#include <string>
+
+#include "components/precache/core/proto/precache.pb.h"
+
+namespace precache {
+
+void RemoveUnknownFields(PrecacheManifest* manifest) {
+  manifest->mutable_unknown_fields()->clear();
+  for (auto& resource : *manifest->mutable_resource())
+    resource.mutable_unknown_fields()->clear();
+  if (manifest->has_experiments()) {
+    manifest->mutable_experiments()->mutable_unknown_fields()->clear();
+    for (auto& kv : *manifest->mutable_experiments()
+                         ->mutable_resources_by_experiment_group()) {
+      kv.second.mutable_unknown_fields()->clear();
+    }
+  }
+  if (manifest->has_id())
+    manifest->mutable_id()->mutable_unknown_fields()->clear();
+}
+
+base::Optional<std::vector<bool>> GetResourceBitset(
+    const PrecacheManifest& manifest,
+    uint32_t experiment_id) {
+  base::Optional<std::vector<bool>> ret;
+  if (manifest.has_experiments()) {
+    const auto& resource_bitset_map =
+        manifest.experiments().resources_by_experiment_group();
+    const auto& it = resource_bitset_map.find(experiment_id);
+    if (it != resource_bitset_map.end()) {
+      if (it->second.has_bitset()) {
+        const std::string& bitset = it->second.bitset();
+        ret.emplace(bitset.size() * 8);
+        for (size_t i = 0; i < bitset.size(); ++i) {
+          for (size_t j = 0; j < 8; ++j) {
+            if ((1 << j) & bitset[i])
+              ret.value()[i * 8 + j] = true;
+          }
+        }
+      } else if (it->second.has_deprecated_bitset()) {
+        uint64_t bitset = it->second.deprecated_bitset();
+        ret.emplace(64);
+        for (int i = 0; i < 64; ++i) {
+          if ((0x1ULL << i) & bitset)
+            ret.value()[i] = true;
+        }
+      }
+    }
+  }
+  // Only return one variable to ensure RVO triggers.
+  return ret;
+}
+
+}  // namespace precache