[Experiment] purge-and-suspend

cc/tiles/gpu_image_decode_controller.h

Index: cc/tiles/gpu_image_decode_controller.h
diff --git a/cc/tiles/gpu_image_decode_controller.h b/cc/tiles/gpu_image_decode_controller.h
index 345de1143573507e09cb430a4a89f854a039099c..9e346c1310743c851343a93588f4674ba15fff84 100644
--- a/cc/tiles/gpu_image_decode_controller.h
+++ b/cc/tiles/gpu_image_decode_controller.h
@@ -11,6 +11,7 @@
 
 #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"
@@ -301,6 +302,9 @@ class CC_EXPORT GpuImageDecodeController
                               ImageData* image_data);
   void DeletePendingImages();
 
+  void OnMemoryPressure(
+      base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
+
   const ResourceFormat format_;
   ContextProvider* context_;
   sk_sp<GrContextThreadSafeProxy> context_threadsafe_proxy_;
@@ -327,6 +331,8 @@ class CC_EXPORT GpuImageDecodeController
   // 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