Update from https://crrev.com/316786

base/memory/discardable_memory_mac.cc

Index: base/memory/discardable_memory_mac.cc
diff --git a/base/memory/discardable_memory_mac.cc b/base/memory/discardable_memory_mac.cc
index 18cf80ac4aa80cf2fbae99d755b05fb7127e8ebf..c8669a6c553f1dac753a5f2adf949edab4a28728 100644
--- a/base/memory/discardable_memory_mac.cc
+++ b/base/memory/discardable_memory_mac.cc
@@ -14,11 +14,6 @@
 namespace base {
 
 // static
-void DiscardableMemory::ReleaseFreeMemory() {
-  internal::DiscardableMemoryShmem::ReleaseFreeMemory();
-}
-
-// static
 bool DiscardableMemory::ReduceMemoryUsage() {
   return internal::DiscardableMemoryEmulated::ReduceMemoryUsage();
 }
@@ -72,11 +67,4 @@ scoped_ptr<DiscardableMemory> DiscardableMemory::CreateLockedMemoryWithType(
   return nullptr;
 }
 
-// static
-void DiscardableMemory::PurgeForTesting() {
-  internal::DiscardableMemoryMach::PurgeForTesting();
-  internal::DiscardableMemoryEmulated::PurgeForTesting();
-  internal::DiscardableMemoryShmem::PurgeForTesting();
-}
-
 }  // namespace base