Add discardable memory emulation for non-android/mac platforms

base/memory/discardable_memory.cc

 // Copyright (c) 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 "base/memory/discardable_memory.h"
 
 #include "base/logging.h"
 
 namespace base {
 
 DiscardableMemory::DiscardableMemory()
     : memory_(NULL),
       size_(0),
       is_locked_(false)
 #if defined(OS_ANDROID)
       , fd_(-1)
 #endif  // OS_ANDROID
       {
-  DCHECK(Supported());
 }
 
 void* DiscardableMemory::Memory() const {
-  DCHECK(is_locked_);
+  // Vending a pointer to unlocked memory is a fatal error and we must die.
+  CHECK(is_locked_);
   return memory_;
 }
 
-// Stub implementations for platforms that don't support discardable memory.
-
-#if !defined(OS_ANDROID) && !defined(OS_MACOSX)
-
-DiscardableMemory::~DiscardableMemory() {
-  NOTIMPLEMENTED();
-}
-
-// static
-bool DiscardableMemory::Supported() {
-  return false;
-}
-
-bool DiscardableMemory::InitializeAndLock(size_t size) {
-  NOTIMPLEMENTED();
-  return false;
-}
-
-LockDiscardableMemoryStatus DiscardableMemory::Lock() {
-  NOTIMPLEMENTED();
-  return DISCARDABLE_MEMORY_FAILED;
-}
-
-void DiscardableMemory::Unlock() {
-  NOTIMPLEMENTED();
-}
-
-// static
-bool DiscardableMemory::PurgeForTestingSupported() {
-  return false;
-}
-
-// static
-void DiscardableMemory::PurgeForTesting() {
-  NOTIMPLEMENTED();
-}
-
-#endif  // OS_*
-
 }  // namespace base