Revert of Use DiscardableMemoryManager on Android.

base/memory/discardable_memory_linux.cc

Index: base/memory/discardable_memory_linux.cc
diff --git a/base/memory/discardable_memory_linux.cc b/base/memory/discardable_memory_linux.cc
index fbd496d6cd4ed2523cd9e19d1dda51d20f37d128..e44b7c20ce0020fa1ba36bb0259e119488f1fe6c 100644
--- a/base/memory/discardable_memory_linux.cc
+++ b/base/memory/discardable_memory_linux.cc
@@ -35,7 +35,7 @@
     DiscardableMemoryType type, size_t size) {
   switch (type) {
     case DISCARDABLE_MEMORY_TYPE_NONE:
-    case DISCARDABLE_MEMORY_TYPE_ASHMEM:
+    case DISCARDABLE_MEMORY_TYPE_ANDROID:
     case DISCARDABLE_MEMORY_TYPE_MAC:
       return scoped_ptr<DiscardableMemory>();
     case DISCARDABLE_MEMORY_TYPE_EMULATED: {
@@ -61,6 +61,11 @@
 }
 
 // static
+bool DiscardableMemory::PurgeForTestingSupported() {
+  return true;
+}
+
+// static
 void DiscardableMemory::PurgeForTesting() {
   internal::DiscardableMemoryEmulated::PurgeForTesting();
 }