[Experiment] purge-and-suspend

cc/tiles/gpu_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_GPU_IMAGE_DECODE_CONTROLLER_H_
 #define CC_TILES_GPU_IMAGE_DECODE_CONTROLLER_H_
 
 #include <memory>
 #include <unordered_map>
 #include <vector>
 
 #include "base/containers/mru_cache.h"
 #include "base/memory/discardable_memory.h"
+#include "base/memory/memory_pressure_listener.h"
 #include "base/synchronization/lock.h"
 #include "base/trace_event/memory_dump_provider.h"
 #include "cc/base/cc_export.h"
 #include "cc/resources/resource_format.h"
 #include "cc/tiles/image_decode_controller.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
 
 class SkImageTextureData;
 
 namespace cc {
@@ skipping 270 matching lines @@
   // Returns true if the given ImageData can be used to draw the specified
   // DrawImage.
   bool IsCompatible(const ImageData* image_data,
                     const DrawImage& draw_image) const;
 
   // The following two functions also require the |context_| lock to be held.
   void UploadImageIfNecessary(const DrawImage& draw_image,
                               ImageData* image_data);
   void DeletePendingImages();
 
+  void OnMemoryPressure(
+      base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
+
   const ResourceFormat format_;
   ContextProvider* context_;
   sk_sp<GrContextThreadSafeProxy> context_threadsafe_proxy_;
 
   // All members below this point must only be accessed while holding |lock_|.
   base::Lock lock_;
 
   // |persistent_cache_| represents the long-lived cache, keeping a certain
   // budget of ImageDatas alive even when their ref count reaches zero.
   using PersistentCache = base::MRUCache<uint32_t, scoped_refptr<ImageData>>;
   PersistentCache persistent_cache_;
 
   // |in_use_cache_| represents the in-use (short-lived) cache. Entries are
   // cleaned up as soon as their ref count reaches zero.
   using InUseCache = std::unordered_map<InUseCacheKey, InUseCacheEntry>;
   InUseCache in_use_cache_;
 
   size_t cached_items_limit_;
   size_t cached_bytes_limit_;
   size_t bytes_used_;
   const size_t max_gpu_image_bytes_;
 
   // We can't release GPU backed SkImages without holding the context lock,
   // so we add them to this list and defer deletion until the next time the lock
   // is held.
   std::vector<sk_sp<SkImage>> images_pending_deletion_;
+
+  std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_GPU_IMAGE_DECODE_CONTROLLER_H_