Add DiscardableMemoryAllocator to work around FD limit issue.

base/memory/discardable_memory_allocator.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 "base/memory/discardable_memory_allocator.h"
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/discardable_memory.h"
+#include "build/build_config.h"
+
+namespace base {
+
+#if !defined(OS_ANDROID)
+
+namespace {
+
+class DiscardableMemoryAllocatorImpl : public DiscardableMemoryAllocator {
+ public:
+  DiscardableMemoryAllocatorImpl() {}
+  virtual ~DiscardableMemoryAllocatorImpl() {}
+
+  // DiscardableMemoryAllocator:
+  virtual scoped_ptr<DiscardableMemory> Allocate(size_t size) OVERRIDE {
+    return DiscardableMemory::CreateLockedMemory(size);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryAllocatorImpl);
+};
+
+}  // namespace
+
+// static
+scoped_ptr<DiscardableMemoryAllocator> DiscardableMemoryAllocator::Create(
+    const std::string& name) {
+  return scoped_ptr<DiscardableMemoryAllocator>(
+      new DiscardableMemoryAllocatorImpl());
+}
+
+#endif
+
+}  // namespace base