policy_fuzzer: Fix compilation after Entry update

Fix the policy_fuzzer to use the new accessor interface of the
PolicyMap::Entry class.

Bug: 1083984
Change-Id: I0dae1ac3ecc39ca4cab89ffc937dd4081e077580
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2218316
Auto-Submit: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Maksim Ivanov <emaxx@chromium.org>
Commit-Queue: Aya Elsayed <ayaelattar@google.com>
Reviewed-by: Aya Elsayed <ayaelattar@google.com>
Cr-Commit-Position: refs/heads/master@{#773112}

chrome/browser/chromeos/policy/fuzzer/policy_fuzzer.cc

@@ -39,7 +39,7 @@ DEFINE_PROTO_FUZZER(const PolicyFuzzerProto& proto) {
     for (const auto& it : policy_map) {
       const std::string& policy_name = it.first;
       const PolicyMap::Entry& entry = it.second;
-      CHECK(entry.value) << "Policy " << policy_name << " has an empty value";
+      CHECK(entry.value()) << "Policy " << policy_name << " has an empty value";
       CHECK_EQ(entry.scope, POLICY_SCOPE_MACHINE)
           << "Policy " << policy_name << " has not machine scope";
     }
@@ -57,7 +57,7 @@ DEFINE_PROTO_FUZZER(const PolicyFuzzerProto& proto) {
     for (const auto& it : policy_map) {
       const std::string& policy_name = it.first;
       const PolicyMap::Entry& entry = it.second;
-      CHECK(entry.value) << "Policy " << policy_name << " has an empty value";
+      CHECK(entry.value()) << "Policy " << policy_name << " has an empty value";
       CHECK_EQ(entry.scope, POLICY_SCOPE_USER)
           << "Policy " << policy_name << " has not user scope";
     }