Memory-monitor for Mac.

content/browser/memory/memory_monitor.h

Index: content/browser/memory/memory_monitor.h
diff --git a/content/browser/memory/memory_monitor.h b/content/browser/memory/memory_monitor.h
index a9d0f211fe24e83466b31b8113ba51a8119b7f52..7419e5355fddce73f59d61c328ac450bd1159ceb 100644
--- a/content/browser/memory/memory_monitor.h
+++ b/content/browser/memory/memory_monitor.h
@@ -51,6 +51,10 @@ class CONTENT_EXPORT MemoryMonitorDelegate {
   // Returns system memory information.
   virtual void GetSystemMemoryInfo(base::SystemMemoryInfoKB* mem_info);
 
+  // Gets the system memory-pressure information. Returns true if successful
+  // or false otherwise.

[chrisha, 2016/11/14 18:14:31]

Expand the comment that this is only defined on some platforms, and that the
meaning of the value is very much OS specific?

[bcwhite, 2016/11/15 23:15:09]

Done.

+  virtual bool GetSystemMemoryPressure(int* mem_pressure);

[chrisha, 2016/11/09 21:21:11]

Can't we push this to the MemoryMonitorMacDelegate specialization?

[bcwhite, 2016/11/09 22:46:54]

I tried that but it makes tests problematic because they use classes derived
from TestMemoryMonitorDelegate which derives from MemoryMonitorDelegate.  So in
order to both override this method and have access to the common test code, this
interface has to define both.

+
  private:
   friend struct base::DefaultSingletonTraits<MemoryMonitorDelegate>;