Add discardable memory emulation for non-android/mac platforms

skia/ext/SkDiscardableMemory_chrome.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "SkDiscardableMemory_chrome.h"
 
 SkDiscardableMemoryChrome::SkDiscardableMemoryChrome()
     : discardable_(new base::DiscardableMemory()) {
 }
 
@@ skipping 20 matching lines @@
 
 void SkDiscardableMemoryChrome::unlock() {
   discardable_->Unlock();
 }
 
 bool SkDiscardableMemoryChrome::InitializeAndLock(size_t bytes) {
   return discardable_->InitializeAndLock(bytes);
 }
 
 SkDiscardableMemory* SkDiscardableMemory::Create(size_t bytes) {
-  if (!base::DiscardableMemory::Supported()) {
-    return NULL;
-  }
   scoped_ptr<SkDiscardableMemoryChrome> discardable(
       new SkDiscardableMemoryChrome());
   if (discardable->InitializeAndLock(bytes))
     return discardable.release();
   return NULL;
 }