[Experiment] purge-and-suspend

cc/resources/resource_pool.cc

Index: cc/resources/resource_pool.cc
diff --git a/cc/resources/resource_pool.cc b/cc/resources/resource_pool.cc
index 0ec24005a49e8e40af31fc771f559a69fbd83845..57a42b8c7dede44201d3571cf22ca4d105db7bed 100644
--- a/cc/resources/resource_pool.cc
+++ b/cc/resources/resource_pool.cc
@@ -10,6 +10,7 @@
 #include <algorithm>
 #include <utility>
 
+#include "base/allocator/allocator_extension.h"
 #include "base/format_macros.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ -75,6 +76,9 @@ ResourcePool::ResourcePool(ResourceProvider* resource_provider,
       weak_ptr_factory_(this) {
   base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
       this, "cc::ResourcePool", task_runner_.get());
+
+  memory_pressure_listener_.reset(new base::MemoryPressureListener(
+      base::Bind(&ResourcePool::OnMemoryPressure, base::Unretained(this))));
 }
 
 ResourcePool::~ResourcePool() {
@@ -224,6 +228,13 @@ void ResourcePool::SetResourceUsageLimits(size_t max_memory_usage_bytes,
   ReduceResourceUsage();
 }
 
+void ResourcePool::OnMemoryPressure(
+    base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
+  while (!unused_resources_.empty())
+    DeleteResource(PopBack(&unused_resources_));
+  base::allocator::ReleaseFreeMemory();
+}
+
 void ResourcePool::ReduceResourceUsage() {
   while (!unused_resources_.empty()) {
     if (!ResourceUsageTooHigh())