base: Rename discardable memory allocator interface and remove unnecessary class.

base/memory/discardable_memory_shmem.h

Index: base/memory/discardable_memory_shmem.h
diff --git a/base/memory/discardable_memory_shmem.h b/base/memory/discardable_memory_shmem.h
deleted file mode 100644
index f3945626a9270e8729ebbb16bd66acc9363b5c0c..0000000000000000000000000000000000000000
--- a/base/memory/discardable_memory_shmem.h
+++ /dev/null
@@ -1,37 +0,0 @@
-// Copyright 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.
-
-#ifndef BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_H_
-#define BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_H_
-
-#include "base/memory/discardable_memory.h"
-
-namespace base {
-class DiscardableMemoryShmemChunk;
-
-namespace internal {
-
-class DiscardableMemoryShmem : public DiscardableMemory {
- public:
-  explicit DiscardableMemoryShmem(size_t bytes);
-  ~DiscardableMemoryShmem() override;
-
-  bool Initialize();
-
-  // Overridden from DiscardableMemory:
-  bool Lock() override;
-  void Unlock() override;
-  void* Memory() const override;
-
- private:
-  scoped_ptr<DiscardableMemoryShmemChunk> chunk_;
-  bool is_locked_;
-
-  DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryShmem);
-};
-
-}  // namespace internal
-}  // namespace base
-
-#endif  // BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_H_