Re-land: base: Enable browser-wide discardable memory on Linux, CrOS and Windows.

base/memory/discardable_memory_win.cc

Index: base/memory/discardable_memory_win.cc
diff --git a/base/memory/discardable_memory_win.cc b/base/memory/discardable_memory_win.cc
index 9b4e9401ce4ff7c006756a9a5ed6a245431662c9..863c6db37fa2bc14933a60816a766568b5875533 100644
--- a/base/memory/discardable_memory_win.cc
+++ b/base/memory/discardable_memory_win.cc
@@ -24,8 +24,8 @@ bool DiscardableMemory::ReduceMemoryUsage() {
 void DiscardableMemory::GetSupportedTypes(
     std::vector<DiscardableMemoryType>* types) {
   const DiscardableMemoryType supported_types[] = {
-    DISCARDABLE_MEMORY_TYPE_EMULATED,
-    DISCARDABLE_MEMORY_TYPE_SHMEM
+    DISCARDABLE_MEMORY_TYPE_SHMEM,
+    DISCARDABLE_MEMORY_TYPE_EMULATED
   };
   types->assign(supported_types, supported_types + arraysize(supported_types));
 }