Re-land: base: Fix registering of memory pressure listeners used when emulating discardable memory.

base/memory/discardable_memory_linux.cc

Index: base/memory/discardable_memory_linux.cc
diff --git a/base/memory/discardable_memory_linux.cc b/base/memory/discardable_memory_linux.cc
index 33c85bdcb86450e16c8463ea553c689ea113b609..6ae9483ca92a141a3eedf6974c9121a386e9b0c3 100644
--- a/base/memory/discardable_memory_linux.cc
+++ b/base/memory/discardable_memory_linux.cc
@@ -10,6 +10,16 @@
 namespace base {
 
 // static
+void DiscardableMemory::RegisterMemoryPressureListeners() {
+  internal::DiscardableMemoryEmulated::RegisterMemoryPressureListeners();
+}
+
+// static
+void DiscardableMemory::UnregisterMemoryPressureListeners() {
+  internal::DiscardableMemoryEmulated::UnregisterMemoryPressureListeners();
+}
+
+// static
 void DiscardableMemory::GetSupportedTypes(
     std::vector<DiscardableMemoryType>* types) {
   const DiscardableMemoryType supported_types[] = {