Move html_viewer from mojo/services to components.

mojo/services/html_viewer/discardable_memory_allocator.h

-// Copyright 2015 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 MOJO_SERVICES_HTML_VIEWER_DISCARDABLE_MEMORY_ALLOCATOR_H_
-#define MOJO_SERVICES_HTML_VIEWER_DISCARDABLE_MEMORY_ALLOCATOR_H_
-
-#include <list>
-
-#include "base/memory/discardable_memory_allocator.h"
-
-namespace html_viewer {
-
-// A discarable memory allocator which will unallocate chunks on new
-// allocations.
-class DiscardableMemoryAllocator : public base::DiscardableMemoryAllocator {
- public:
-  class OwnedMemoryChunk;
-
-  explicit DiscardableMemoryAllocator(size_t desired_max_memory);
-  ~DiscardableMemoryAllocator() override;
-
-  // Overridden from DiscardableMemoryAllocator:
-  scoped_ptr<base::DiscardableMemory> AllocateLockedDiscardableMemory(
-      size_t size) override;
-
- private:
-  friend class OwnedMemoryChunk;
-
-  // Called by OwnedMemoryChunks when they are unlocked. This puts them at the
-  // end of the live_unlocked_chunks_ list and passes an iterator to their
-  // position in the unlocked chunk list.
-  std::list<OwnedMemoryChunk*>::iterator NotifyUnlocked(
-      OwnedMemoryChunk* chunk);
-
-  // Called by OwnedMemoryChunks when they are locked. This removes the passed
-  // in unlocked chunk list.
-  void NotifyLocked(std::list<OwnedMemoryChunk*>::iterator it);
-
-  // The amount of memory we can allocate before we try to free unlocked
-  // chunks. We can go over this amount if all callers keep their discardable
-  // chunks locked.
-  const size_t desired_max_memory_;
-
-  // A count of the sum of memory. Used to trigger discarding the oldest
-  // memory.
-  size_t total_live_memory_;
-
-  // The number of locked chunks.
-  int locked_chunks_;
-
-  // A linked list of unlocked allocated chunks so that the tail is most
-  // recently accessed chunks.
-  std::list<OwnedMemoryChunk*> live_unlocked_chunks_;
-
-  DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryAllocator);
-};
-
-}  // namespace html_viewer
-
-#endif  // MOJO_SERVICES_HTML_VIEWER_DISCARDABLE_MEMORY_ALLOCATOR_H_