Re-land: base: Implement browser process support for discardable memory.

chrome/test/base/chrome_unit_test_suite.cc

Index: chrome/test/base/chrome_unit_test_suite.cc
diff --git a/chrome/test/base/chrome_unit_test_suite.cc b/chrome/test/base/chrome_unit_test_suite.cc
index c78d463eed706df8b95261d58c78dc69ac546ed4..2ce04bd0b7c8dcfe442ef7ed07aacdb8bc297e3b 100644
--- a/chrome/test/base/chrome_unit_test_suite.cc
+++ b/chrome/test/base/chrome_unit_test_suite.cc
@@ -110,6 +110,9 @@ void ChromeUnitTestSuite::Initialize() {
   // This needs to run after ChromeTestSuite::Initialize which calls content's
   // intialization which calls base's which initializes ICU.
   InitializeResourceBundle();
+
+  base::DiscardableMemoryShmemAllocator::SetInstance(
+      &discardable_memory_allocator_);
 }
 
 void ChromeUnitTestSuite::Shutdown() {