Using the new MemoryPressureListener instead of the LowMemoryObserver when the enhanced memory mana…

content/public/browser/browser_thread.h

Index: content/public/browser/browser_thread.h
diff --git a/content/public/browser/browser_thread.h b/content/public/browser/browser_thread.h
index 8daa0dbc916b501356734f8c73dbdc14275dd1b3..6d622873424887cef1366f739f0c9677dbcd24eb 100644
--- a/content/public/browser/browser_thread.h
+++ b/content/public/browser/browser_thread.h
@@ -20,6 +20,9 @@ namespace base {
 class MessageLoop;
 class SequencedWorkerPool;
 class Thread;
+#if defined(OS_CHROMEOS)
+class MemoryPressureObserverChromeOS;
+#endif
 }
 
 namespace content {
@@ -152,6 +155,10 @@ class CONTENT_EXPORT BrowserThread {
         from_here, object);
   }
 
+#if defined(OS_CHROMEOS)
+  static base::MemoryPressureObserverChromeOS* GetMemoryPressureObserver();
+#endif

[piman, 2014/12/20 02:53:15]

This doesn't really look like it belongs to BrowserThread.

Should it be a top-level free function?


Also, it would be nice if this was not a ChromeOS-only interface.

[Mr4D (OOO till 08-26), 2014/12/20 03:01:05]

Sure - we could also do it that way. Do you prefer top level free?

After long consideration I thought that BrowserThread was a good fit.

For the interface:
That was what I initially intended. That was the reason for me to put it into a
public (base) place. But since this could not be done for Android I was told to
only do this for ChromeOS. Should we reconsider and do it for all OS'es?

[piman, 2014/12/20 03:05:17]

I think I would prefer top-level free.
This doesn't seem to fit with other members of this class.
Also, it's not looking up a member of BrowserThreadImpl. So it really feels
unrelated.

See e.g. content::GetContextFactory
I would prefer if we didn't have #ifdef warts in public APIs. In the future it's
not inconceivable that we can support the memory pressure logic, or at least a
subset, on other platforms.

[Mr4D (OOO till 08-26), 2015/01/06 22:22:06]

Done that way.

However - I still believe that this object should be a global base:: singleton
accessible from everywhere - this object is a rather obvious thing which could
be used from everywhere (even from base).

Also - yes, I was trying to make this object OS unaware, but that change  was
rejected. If we ever want to make this uniform for all OS'es I am all for it.

+
   // Simplified wrappers for posting to the blocking thread pool. Use this
   // for doing things like blocking I/O.
   //