Revert of base: Introduce an explicit call for reducing emulated discardable memory usage.

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 578b2c1c756049559e902300dffe1ddf51a82635..b9342e92043cad68ba0470e201e35d94d116613a 100644
--- a/base/memory/discardable_memory_linux.cc
+++ b/base/memory/discardable_memory_linux.cc
@@ -9,6 +9,16 @@
 #include "base/memory/discardable_memory_malloc.h"
 
 namespace base {
+
+// static
+void DiscardableMemory::RegisterMemoryPressureListeners() {
+  internal::DiscardableMemoryEmulated::RegisterMemoryPressureListeners();
+}
+
+// static
+void DiscardableMemory::UnregisterMemoryPressureListeners() {
+  internal::DiscardableMemoryEmulated::UnregisterMemoryPressureListeners();
+}
 
 // static
 bool DiscardableMemory::ReduceMemoryUsage() {