Re-land: base: Fix registering of memory pressure listeners used when emulating discardable memory.

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 "base/run_loop.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #if defined(OS_ANDROID)
 #include <limits>
 #endif
 
 namespace base {
 namespace {
 
 class DiscardableMemoryTest
     : public testing::TestWithParam<DiscardableMemoryType> {
+ public:
+  DiscardableMemoryTest() : message_loop_(MessageLoop::TYPE_IO) {
+    // Register memory pressure listeners now that we have a message loop.
+    DiscardableMemory::RegisterMemoryPressureListeners();
+  }
+  virtual ~DiscardableMemoryTest() {
+    DiscardableMemory::UnregisterMemoryPressureListeners();
+  }
+
  protected:
   scoped_ptr<DiscardableMemory> CreateLockedMemory(size_t size) {
     return DiscardableMemory::CreateLockedMemoryWithType(
         GetParam(), size).Pass();
   }
+
+ private:
+  MessageLoop message_loop_;
 };
 
 const size_t kSize = 1024;
 
 TEST_P(DiscardableMemoryTest, IsNamed) {
   std::string type_name(DiscardableMemory::GetTypeName(GetParam()));
   EXPECT_NE("unknown", type_name);
   EXPECT_EQ(GetParam(), DiscardableMemory::GetNamedType(type_name));
 }
 
@@ skipping 75 matching lines @@
   return supported_types;
 }
 
 INSTANTIATE_TEST_CASE_P(
     DiscardableMemoryTests,
     DiscardableMemoryTest,
     ::testing::ValuesIn(GetSupportedDiscardableMemoryTypes()));
 
 }  // namespace
 }  // namespace base