[net] Change factory methods for HostResolver and HostCache to return a scoped_ptr

net/base/host_cache.h

Index: net/base/host_cache.h
diff --git a/net/base/host_cache.h b/net/base/host_cache.h
index 7aff49c1ba16dc85cd145c9298ed2314e3ad953e..37d888b03a364917f539e1247380ca9c9e59fdfc 100644
--- a/net/base/host_cache.h
+++ b/net/base/host_cache.h
@@ -9,6 +9,7 @@
 #include <string>
 
 #include "base/gtest_prod_util.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/time.h"
 #include "net/base/address_family.h"
@@ -87,7 +88,7 @@ class NET_EXPORT HostCache : NON_EXPORTED_BASE(public base::NonThreadSafe) {
   const EntryMap& entries() const;
 
   // Creates a default cache.
-  static HostCache* CreateDefaultCache();
+  static scoped_ptr<HostCache> CreateDefaultCache();
 
  private:
   FRIEND_TEST_ALL_PREFIXES(HostCacheTest, NoCache);