Adds MemoryPressureListener.

chrome/browser/memory_purger.h

 // Copyright (c) 2010 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.
 
 // MemoryPurger provides static APIs to purge as much memory as possible from
 // all processes.  These can be hooked to various signals to try and balance
 // memory consumption, speed, page swapping, etc.
 //
 // This was implemented in an attempt to speed up suspend-to-disk by throwing
 // away any cached data that can be recomputed.  Memory use will rapidly
 // re-expand after this purge is run.
 
 #ifndef CHROME_BROWSER_MEMORY_PURGER_H_
 #define CHROME_BROWSER_MEMORY_PURGER_H_
 
 #include "base/basictypes.h"
 
 namespace content {
 class RenderProcessHost;
 }
 
 class MemoryPurger {
  public:
   // Call any of these on the UI thread to purge memory from the named places.
   static void PurgeAll();
   static void PurgeBrowser();
   static void PurgeRenderers();
   static void PurgeRendererForHost(content::RenderProcessHost* host);
 
+  // Call this to register for a MemoryPressure listener, so that PurgeAll()
+  // is called when the underlying platform send a low memory signal.
+  static void RegisterMemoryPressureListener();

[joth, 2013/06/05 16:51:23]

if this is actually useful it should be in cross-platform code.

[bulach, 2013/06/05 19:02:11]

the registration itself? this file itself is cross-platform..
for the time being, no other platform would send the signal yet, so I think this
will be done as a separate patch.

+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(MemoryPurger);
 };
 
 #endif  // CHROME_BROWSER_MEMORY_PURGER_H_