base: Add discardable memory test that check behavior when creating enough instances that could use…

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 <algorithm>
 
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 85 matching lines @@
 // Death tests are not supported with Android APKs.
 TEST_P(DiscardableMemoryTest, UnlockedMemoryAccessCrashesInDebugMode) {
   const scoped_ptr<DiscardableMemory> memory(CreateLockedMemory(kSize));
   ASSERT_TRUE(memory);
   memory->Unlock();
   ASSERT_DEATH_IF_SUPPORTED(
       { *static_cast<int*>(memory->Memory()) = 0xdeadbeef; }, ".*");
 }
 #endif
 
+// Test behavior when creating enough instances that could use up a 32-bit
+// address space.
+TEST_P(DiscardableMemoryTest, AddressSpace) {
+  const size_t kLargeSize = 4 * 1024 * 1024;  // 4MiB.
+  const size_t kNumberOfInstances = 1024 + 1;  // >4GiB total.
+
+  scoped_ptr<DiscardableMemory> instances[kNumberOfInstances];
+  for (auto& memory : instances) {
+    memory = CreateLockedMemory(kLargeSize);
+    ASSERT_TRUE(memory);
+    void* addr = memory->Memory();
+    ASSERT_NE(nullptr, addr);
+    memory->Unlock();
+  }
+}
+
 std::vector<DiscardableMemoryType> GetSupportedDiscardableMemoryTypes() {
   std::vector<DiscardableMemoryType> supported_types;
   DiscardableMemory::GetSupportedTypes(&supported_types);
   return supported_types;
 }
 
 INSTANTIATE_TEST_CASE_P(
     DiscardableMemoryTests,
     DiscardableMemoryTest,
     ::testing::ValuesIn(GetSupportedDiscardableMemoryTypes()));
 
 }  // namespace
 }  // namespace base