Work around a Purify bug by making an object used by NetTestSuite stack alloc...

net/base/host_resolver_unittest.h

Index: net/base/host_resolver_unittest.h
===================================================================
--- net/base/host_resolver_unittest.h	(revision 9313)
+++ net/base/host_resolver_unittest.h	(working copy)
@@ -125,12 +125,20 @@
     current_host_mapper_->set_previous_mapper(previous_host_mapper_.get());
   }
 
+  ScopedHostMapper() {}
+
   ~ScopedHostMapper() {
     HostMapper* old_mapper = SetHostMapper(previous_host_mapper_.get());
     // The lifetimes of multiple instances must be nested.
     CHECK(old_mapper == current_host_mapper_.get());
   }
 
+  void Init(HostMapper* mapper) {
+    current_host_mapper_ = mapper;
+    previous_host_mapper_ = SetHostMapper(current_host_mapper_.get());
+    current_host_mapper_->set_previous_mapper(previous_host_mapper_.get());
+  }
+
  private:
   scoped_refptr<HostMapper> current_host_mapper_;
   scoped_refptr<HostMapper> previous_host_mapper_;