base: Add uncached malloc based discardable memory type.

base/memory/discardable_memory.h

 // Copyright (c) 2013 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.
 
 #ifndef BASE_MEMORY_DISCARDABLE_MEMORY_H_
 #define BASE_MEMORY_DISCARDABLE_MEMORY_H_
 
 #include <string>
 #include <vector>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 
 namespace base {
 
 enum DiscardableMemoryType {
   DISCARDABLE_MEMORY_TYPE_NONE,
   DISCARDABLE_MEMORY_TYPE_ANDROID,
   DISCARDABLE_MEMORY_TYPE_MAC,
-  DISCARDABLE_MEMORY_TYPE_EMULATED
+  DISCARDABLE_MEMORY_TYPE_EMULATED,
+  DISCARDABLE_MEMORY_TYPE_MALLOC
 };
 
 enum DiscardableMemoryLockStatus {
   DISCARDABLE_MEMORY_LOCK_STATUS_FAILED,
   DISCARDABLE_MEMORY_LOCK_STATUS_PURGED,
   DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS
 };
 
 // Platform abstraction for discardable memory. DiscardableMemory is used to
 // cache large objects without worrying about blowing out memory, both on mobile
@@ skipping 86 matching lines @@
   static bool PurgeForTestingSupported();
 
   // Purge all discardable memory in the system. This call has global effects
   // across all running processes, so it should only be used for testing!
   static void PurgeForTesting();
 };
 
 }  // namespace base
 
 #endif  // BASE_MEMORY_DISCARDABLE_MEMORY_H_