Update from chromium https://crrev.com/301315

base/memory/discardable_memory_android.cc

Index: base/memory/discardable_memory_android.cc
diff --git a/base/memory/discardable_memory_android.cc b/base/memory/discardable_memory_android.cc
index 0c9f3fc61d9f9a9f2f0d5200d5fd58906ae3c362..de7112457dea7a17ce0d6483af7dc931168f1261 100644
--- a/base/memory/discardable_memory_android.cc
+++ b/base/memory/discardable_memory_android.cc
@@ -11,6 +11,7 @@
 #include "base/memory/discardable_memory_ashmem.h"
 #include "base/memory/discardable_memory_ashmem_allocator.h"
 #include "base/memory/discardable_memory_emulated.h"
+#include "base/memory/discardable_memory_shmem.h"
 #include "base/sys_info.h"
 
 namespace base {
@@ -43,6 +44,11 @@ LazyInstance<SharedState>::Leaky g_shared_state = LAZY_INSTANCE_INITIALIZER;
 }  // namespace
 
 // static
+void DiscardableMemory::ReleaseFreeMemory() {
+  internal::DiscardableMemoryShmem::ReleaseFreeMemory();
+}
+
+// static
 bool DiscardableMemory::ReduceMemoryUsage() {
   return internal::DiscardableMemoryEmulated::ReduceMemoryUsage();
 }
@@ -52,7 +58,8 @@ void DiscardableMemory::GetSupportedTypes(
     std::vector<DiscardableMemoryType>* types) {
   const DiscardableMemoryType supported_types[] = {
     DISCARDABLE_MEMORY_TYPE_ASHMEM,
-    DISCARDABLE_MEMORY_TYPE_EMULATED
+    DISCARDABLE_MEMORY_TYPE_EMULATED,
+    DISCARDABLE_MEMORY_TYPE_SHMEM
   };
   types->assign(supported_types, supported_types + arraysize(supported_types));
 }
@@ -79,6 +86,14 @@ scoped_ptr<DiscardableMemory> DiscardableMemory::CreateLockedMemoryWithType(
 
       return memory.Pass();
     }
+    case DISCARDABLE_MEMORY_TYPE_SHMEM: {
+      scoped_ptr<internal::DiscardableMemoryShmem> memory(
+          new internal::DiscardableMemoryShmem(size));
+      if (!memory->Initialize())
+        return nullptr;
+
+      return memory.Pass();
+    }
     case DISCARDABLE_MEMORY_TYPE_NONE:
     case DISCARDABLE_MEMORY_TYPE_MACH:
       NOTREACHED();
@@ -93,6 +108,7 @@ scoped_ptr<DiscardableMemory> DiscardableMemory::CreateLockedMemoryWithType(
 void DiscardableMemory::PurgeForTesting() {
   g_shared_state.Pointer()->manager.PurgeAll();
   internal::DiscardableMemoryEmulated::PurgeForTesting();
+  internal::DiscardableMemoryShmem::PurgeForTesting();
 }
 
 }  // namespace base