Update from https://crrev.com/320343

base/memory/discardable_memory_shmem.h

 // 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:
-  DiscardableMemoryLockStatus Lock() override;
+  bool Lock() override;
   void Unlock() override;
   void* Memory() const override;
 
  private:
-  const size_t bytes_;
   scoped_ptr<DiscardableMemoryShmemChunk> chunk_;
   bool is_locked_;
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryShmem);
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_H_