[Experiment] purge-and-suspend

cc/tiles/software_image_decode_controller.h

 // Copyright 2016 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 CC_TILES_SOFTWARE_IMAGE_DECODE_CONTROLLER_H_
 #define CC_TILES_SOFTWARE_IMAGE_DECODE_CONTROLLER_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <unordered_map>
 #include <unordered_set>
 
 #include "base/atomic_sequence_num.h"
 #include "base/containers/mru_cache.h"
 #include "base/hash.h"
 #include "base/memory/discardable_memory_allocator.h"
+#include "base/memory/memory_pressure_listener.h"
 #include "base/memory/ref_counted.h"
 #include "base/numerics/safe_math.h"
 #include "base/threading/thread_checker.h"
 #include "base/trace_event/memory_dump_provider.h"
 #include "cc/base/cc_export.h"
 #include "cc/playback/decoded_draw_image.h"
 #include "cc/playback/draw_image.h"
 #include "cc/resources/resource_format.h"
 #include "cc/tiles/image_decode_controller.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
@@ skipping 216 matching lines @@
   void SanityCheckState(int line, bool lock_acquired);
   void RefImage(const ImageKey& key);
   void RefAtRasterImage(const ImageKey& key);
   void UnrefAtRasterImage(const ImageKey& key);
 
   // Helper function which dumps all images in a specific ImageMRUCache.
   void DumpImageMemoryForCache(const ImageMRUCache& cache,
                                const char* cache_name,
                                base::trace_event::ProcessMemoryDump* pmd) const;
 
+  void OnMemoryPressure(
+      base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
+
   std::unordered_map<ImageKey, scoped_refptr<TileTask>, ImageKeyHash>
       pending_image_tasks_;
 
   // The members below this comment can only be accessed if the lock is held to
   // ensure that they are safe to access on multiple threads.
   base::Lock lock_;
 
   // Decoded images and ref counts (predecode path).
   ImageMRUCache decoded_images_;
   std::unordered_map<ImageKey, int, ImageKeyHash> decoded_images_ref_counts_;
 
   // Decoded image and ref counts (at-raster decode path).
   ImageMRUCache at_raster_decoded_images_;
   std::unordered_map<ImageKey, int, ImageKeyHash>
       at_raster_decoded_images_ref_counts_;
 
   MemoryBudget locked_images_budget_;
 
   ResourceFormat format_;
 
   // Used to uniquely identify DecodedImages for memory traces.
   base::AtomicSequenceNumber next_tracing_id_;
+
+  std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_SOFTWARE_IMAGE_DECODE_CONTROLLER_H_