Use DiscardableMemoryManager on Android.

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 e44b7c20ce0020fa1ba36bb0259e119488f1fe6c..05240ff96041345b72957b33ee5613ded3481823 100644
--- a/base/memory/discardable_memory_win.cc
+++ b/base/memory/discardable_memory_win.cc
@@ -61,13 +61,24 @@ scoped_ptr<DiscardableMemory> DiscardableMemory::CreateLockedMemoryWithType(
 }
 
 // static
-bool DiscardableMemory::PurgeForTestingSupported() {
-  return true;
+bool DiscardableMemory::PurgeForTestingSupported(DiscardableMemoryType type) {
+  switch (type) {
+    case DISCARDABLE_MEMORY_TYPE_EMULATED:
+      return true;
+    default:
+      return false;
+  }
 }
 
 // static
-void DiscardableMemory::PurgeForTesting() {
-  internal::DiscardableMemoryEmulated::PurgeForTesting();
+void DiscardableMemory::PurgeForTesting(DiscardableMemoryType type) {
+  switch (type) {
+    case DISCARDABLE_MEMORY_TYPE_EMULATED:
+      internal::DiscardableMemoryEmulated::PurgeForTesting();
+      return;
+    default:
+      NOTREACHED();
+  }
 }
 
 }  // namespace base