[Experiment] purge-and-suspend

cc/resources/resource_pool.h

Index: cc/resources/resource_pool.h
diff --git a/cc/resources/resource_pool.h b/cc/resources/resource_pool.h
index 74262dedcf90fe0025b369a507b7cd6d511cdcae..64827e316a434aee784b00ded810170605013b65 100644
--- a/cc/resources/resource_pool.h
+++ b/cc/resources/resource_pool.h
@@ -13,6 +13,7 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "base/memory/memory_pressure_listener.h"
 #include "base/memory/ptr_util.h"
 #include "base/trace_event/memory_dump_provider.h"
 #include "cc/base/cc_export.h"
@@ -104,6 +105,8 @@ class CC_EXPORT ResourcePool : public base::trace_event::MemoryDumpProvider {
 
   void DidFinishUsingResource(std::unique_ptr<PoolResource> resource);
   void DeleteResource(std::unique_ptr<PoolResource> resource);
+  void OnMemoryPressure(
+      base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
 
   // Functions which manage periodic eviction of expired resources.
   void ScheduleEvictExpiredResourcesIn(base::TimeDelta time_from_now);
@@ -125,6 +128,8 @@ class CC_EXPORT ResourcePool : public base::trace_event::MemoryDumpProvider {
   ResourceDeque unused_resources_;
   ResourceDeque busy_resources_;
 
+  std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
+
   std::map<ResourceId, std::unique_ptr<PoolResource>> in_use_resources_;
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;