Add DiscardableMemoryAllocator to work around FD limit issue.

base/memory/discardable_memory_unittest.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 <limits>
+
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 
 const size_t kSize = 1024;
 
+TEST(DiscardableMemoryTest, TooLargeAllocationFails) {

[reveman, 2013/12/05 23:21:40]

The addition of this test is causing emulated discardable memory to behave bad
and the LockAndUnLock test below will fail if run after this test. Is this test
really valid on all platforms? max_allowed_allocation_size seem to be very
implementation specific.

+  const size_t kPageSize = 4096;
+  const size_t max_allowed_allocation_size =
+      std::numeric_limits<size_t>::max() - kPageSize + 1;
+  scoped_ptr<DiscardableMemory> memory(
+      DiscardableMemory::CreateLockedMemory(max_allowed_allocation_size + 1));
+  // On certain platforms (e.g. Android), page-alignment would have caused an
+  // overflow resulting in a small allocation if the input size wasn't checked
+  // correctly.
+  ASSERT_FALSE(memory);
+}
+
 TEST(DiscardableMemoryTest, SupportedNatively) {
 #if defined(DISCARDABLE_MEMORY_ALWAYS_SUPPORTED_NATIVELY)
   ASSERT_TRUE(DiscardableMemory::SupportedNatively());
 #else
   // If we ever have a platform that decides at runtime if it can support
   // discardable memory natively, then we'll have to add a 'never supported
   // natively' define for this case. At present, if it's not always supported
   // natively, it's never supported.
   ASSERT_FALSE(DiscardableMemory::SupportedNatively());
 #endif
@@ skipping 45 matching lines @@
   const scoped_ptr<DiscardableMemory> memory(
       DiscardableMemory::CreateLockedMemory(kSize));
   ASSERT_TRUE(memory);
   memory->Unlock();
   ASSERT_DEATH_IF_SUPPORTED(
       { *static_cast<int*>(memory->Memory()) = 0xdeadbeef; }, ".*");
 }
 #endif
 
 }