Purge browser cache for dom storage in a smarter way

content/browser/dom_storage/dom_storage_context_impl.cc

Index: content/browser/dom_storage/dom_storage_context_impl.cc
diff --git a/content/browser/dom_storage/dom_storage_context_impl.cc b/content/browser/dom_storage/dom_storage_context_impl.cc
index 1e6afa770e521e38a77f85825d066a4760759e4e..469e71f35b423e9b6d1c3092d895e98c65a2499f 100644
--- a/content/browser/dom_storage/dom_storage_context_impl.cc
+++ b/content/browser/dom_storage/dom_storage_context_impl.cc
@@ -396,6 +396,19 @@ void DOMStorageContextImpl::StartScavengingUnusedSessionStorage() {
   }
 }
 
+void DOMStorageContextImpl::OnMemoryPressure(
+    base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
+  if (is_shutdown_)
+    return;
+
+  DOMStorageNamespace::PurgeOption option = DOMStorageNamespace::PURGE_UNOPENED;
+  if (memory_pressure_level ==
+      base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL)
+    option = DOMStorageNamespace::PURGE_AGGRESSIVE;
+  for (const auto& it : namespaces_)
+    it.second->PurgeMemory(option);
+}
+
 bool DOMStorageContextImpl::OnMemoryDump(
     const base::trace_event::MemoryDumpArgs& args,
     base::trace_event::ProcessMemoryDump* pmd) {