Remove base::ScopedPtrHashMap from components/policy/.

components/policy/core/common/policy_namespace.h

Index: components/policy/core/common/policy_namespace.h
diff --git a/components/policy/core/common/policy_namespace.h b/components/policy/core/common/policy_namespace.h
index d3d70506fef0a951ea12966182da2bd7aa6a31b3..780fa22f9593f27f8c9103d45081c6064d7431f5 100644
--- a/components/policy/core/common/policy_namespace.h
+++ b/components/policy/core/common/policy_namespace.h
@@ -54,20 +54,13 @@ struct POLICY_EXPORT PolicyNamespace {
 
 typedef std::vector<PolicyNamespace> PolicyNamespaceList;
 
-}  // namespace policy
-
-// Define a custom std::hash for PolicyNamespace so that it can be used as
-// a key in hash_maps, and in particular in ScopedPtrHashMaps (which uses the
-// default std::hash).
-namespace BASE_HASH_NAMESPACE {
-
-template <>
-struct hash<policy::PolicyNamespace> {
-  std::size_t operator()(const policy::PolicyNamespace& ns) const {
-    return hash<std::string>()(ns.component_id) ^ (UINT64_C(1) << ns.domain);
+struct PolicyNamespaceHash {
+  size_t operator()(const policy::PolicyNamespace& ns) const {
+    return std::hash<std::string>()(ns.component_id) ^
+           (UINT64_C(1) << ns.domain);
   }
 };
 
-}  // namespace BASE_HASH_NAMESPACE
+}  // namespace policy
 
 #endif  // COMPONENTS_POLICY_CORE_COMMON_POLICY_NAMESPACE_H_