base: Use DiscardableMemoryManager on MacOSX.

base/memory/discardable_memory_manager_unittest.cc

 // Copyright 2014 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_manager.h"
 
 #include "base/bind.h"
 #include "base/run_loop.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
@@ skipping 26 matching lines @@
 
   bool is_locked() const { return is_locked_; }
 
  private:
   bool is_allocated_;
   bool is_locked_;
 };
 
 class DiscardableMemoryManagerTestBase {
  public:
-  DiscardableMemoryManagerTestBase() {
+  DiscardableMemoryManagerTestBase()
+      : manager_(64 * 1024 * 1024, 12 * 1024 * 1024) {

[willchan no longer on Chromium, 2014/05/05 22:39:28]

Can you add a comment here for why you chose these values? Is it safe to change?
I suspect that the constants chosen in the tests are tightly coupled to these
constants. If that's true, please note that.

[reveman, 2014/05/06 14:26:46]

Reduced the size of these constants and added a comment to latest patch.

     manager_.RegisterMemoryPressureListener();
   }
 
  protected:
   enum LockStatus {
     LOCK_STATUS_FAILED,
     LOCK_STATUS_PURGED,
     LOCK_STATUS_SUCCESS
   };
 
@@ skipping 359 matching lines @@
            Unretained(this)));
   memory_usage_thread_.message_loop()->PostTask(
       FROM_HERE,
       Bind(&ThreadedDiscardableMemoryManagerTest::SignalHelper,
            Unretained(this)));
   thread_sync_.Wait();
 }
 
 }  // namespace
 }  // namespace base