Update from https://crrev.com/309717

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
index d25f84cb46dbdb364d1a86dbf4c9286c8759d02e..b04c9b1ea6ebe70fb79af1f4f01be675749cc6f7 100644
--- a/base/memory/discardable_memory_shmem.h
+++ b/base/memory/discardable_memory_shmem.h
@@ -10,7 +10,7 @@
 #include "base/memory/discardable_memory_manager.h"
 
 namespace base {
-class DiscardableSharedMemory;
+class DiscardableMemoryShmemChunk;
 
 namespace internal {
 
@@ -19,7 +19,7 @@ class DiscardableMemoryShmem
       public internal::DiscardableMemoryManagerAllocation {
  public:
   explicit DiscardableMemoryShmem(size_t bytes);
-  virtual ~DiscardableMemoryShmem();
+  ~DiscardableMemoryShmem() override;
 
   static void ReleaseFreeMemory();
 
@@ -28,19 +28,19 @@ class DiscardableMemoryShmem
   bool Initialize();
 
   // Overridden from DiscardableMemory:
-  virtual DiscardableMemoryLockStatus Lock() override;
-  virtual void Unlock() override;
-  virtual void* Memory() const override;
+  DiscardableMemoryLockStatus Lock() override;
+  void Unlock() override;
+  void* Memory() const override;
 
   // Overridden from internal::DiscardableMemoryManagerAllocation:
-  virtual bool AllocateAndAcquireLock() override;
-  virtual void ReleaseLock() override;
-  virtual void Purge() override;
-  virtual bool IsMemoryResident() const override;
+  bool AllocateAndAcquireLock() override;
+  void ReleaseLock() override;
+  void Purge() override;
+  bool IsMemoryResident() const override;
 
  private:
   const size_t bytes_;
-  scoped_ptr<DiscardableSharedMemory> shared_memory_;
+  scoped_ptr<DiscardableMemoryShmemChunk> chunk_;
   bool is_locked_;
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryShmem);