Use std::unique_ptr to express ownership of base::Value in PolicyMap::Entry

components/policy/core/common/policy_loader_win.cc

 // Copyright (c) 2014 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/policy/core/common/policy_loader_win.h"
 
 #include <windows.h>
 #include <lm.h>       // For limits.
 #include <ntdsapi.h>  // For Ds[Un]Bind
 #include <rpc.h>      // For struct GUID
@@ skipping 148 matching lines @@
       // Only allow custom update urls in enterprise environments.
       if (!base::LowerCaseEqualsASCII(entry.substr(pos),
                                       kExpectedWebStoreUrl)) {
         entry = kBlockedExtensionPrefix + entry;
         invalid_policies++;
       }
 
       filtered_values->AppendString(entry);
     }
     if (invalid_policies) {
-      policy->Set(key::kExtensionInstallForcelist,
-                  map_entry->level, map_entry->scope, map_entry->source,
-                  filtered_values.release(),
+      policy->Set(key::kExtensionInstallForcelist, map_entry->level,
+                  map_entry->scope, map_entry->source,
+                  std::move(filtered_values),
+                  // TODO(dcheng): Ummm... figure out what this is all about
+                  // when I'm more awake.

[Andrew T Wilson (Slow), 2016/05/03 11:59:03]

What's the concern here?

[dcheng, 2016/05/03 23:40:40]

ExternalDataFetcher is now an owned pointer, so it can't just be passed around
like this. Ordinarily, I would just transfer ownership, but that's not possible
here: PolicyMap::Get() returns a const Entry*.

Instead, I opted to just use Entry::DeepCopy() to build a new entry with the
correct filtered values. From a pure efficiency standpoint, it's probably a bit
suboptimal (since it clones the original Value and then immediately replaces it
with the filtered one), but I figure this code shouldn't be on the hot path
anyway, so the cost shouldn't be too large.

                   map_entry->external_data_fetcher);
 
       const PolicyDetails* details = GetChromePolicyDetails(
           key::kExtensionInstallForcelist);
       UMA_HISTOGRAM_SPARSE_SLOWLY("EnterpriseCheck.InvalidPolicies",
                                   details->id);
     }
   }
 
   for (size_t i = 0; i < arraysize(kInsecurePolicies); ++i) {
@@ skipping 501 matching lines @@
 
 void PolicyLoaderWin::OnObjectSignaled(HANDLE object) {
   DCHECK(object == user_policy_changed_event_.handle() ||
          object == machine_policy_changed_event_.handle())
       << "unexpected object signaled policy reload, obj = "
       << std::showbase << std::hex << object;
   Reload(false);
 }
 
 }  // namespace policy