Moves LowMemoryObserver into chromeos and renames

chromeos/memory/low_memory_listener.h

Index: chromeos/memory/low_memory_listener.h
diff --git a/chrome/browser/chromeos/memory/low_memory_observer.h b/chromeos/memory/low_memory_listener.h
similarity index 36%
rename from chrome/browser/chromeos/memory/low_memory_observer.h
rename to chromeos/memory/low_memory_listener.h
index 65f0235ff36198fd2ae9731afaee3e29d016904d..9d1fe4c5b40f898a4229fa9da318d4839b5feb17 100644
--- a/chrome/browser/chromeos/memory/low_memory_observer.h
+++ b/chromeos/memory/low_memory_listener.h
@@ -2,44 +2,47 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROME_BROWSER_CHROMEOS_MEMORY_LOW_MEMORY_OBSERVER_H_
-#define CHROME_BROWSER_CHROMEOS_MEMORY_LOW_MEMORY_OBSERVER_H_
+#ifndef CHROMEOS_MEMORY_LOW_MEMORY_LISTENER_H_
+#define CHROMEOS_MEMORY_LOW_MEMORY_LISTENER_H_
 
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "chromeos/memory/chromeos_memory_export.h"
 
 namespace chromeos {
 
-class LowMemoryObserverImpl;
+class LowMemoryListenerDelegate;
+class LowMemoryListenerImpl;
 
 ////////////////////////////////////////////////////////////////////////////////
-// LowMemoryObserver
+// LowMemoryListener
 //
 // Class to handle observation of low memory device for changes so that we
-// can get a signal from the kernel about low memory conditions and discard tabs
-// when that happens, instead of waiting for the OOM killer to kill renderers
-// (which is more drastic, but still necessary and possible).
+// can get a signal from the kernel about low memory conditions and notify
+// our delegate, who can take actions such as discarding tabs.
 //
-// This object starts and stops the observation, and can be created or deleted
-// from any thread, but the observation occurs on the FILE thread, and tabs are
-// discarded on the UI thread.
-class LowMemoryObserver {
+// This object is intended to be created and used on the UI thread. All
+// notifications are dispatched on the UI thread.
+class CHROMEOS_MEMORY_EXPORT LowMemoryListener {
  public:
-  LowMemoryObserver();
-  ~LowMemoryObserver();
+  explicit LowMemoryListener(LowMemoryListenerDelegate* delegate);
+  ~LowMemoryListener();
 
   void Start();
   void Stop();
 
-  // Sets the threshold level of the low memory notifier in megabytes.  Setting
-  // to -1 will turn off the low memory notifier.
-  static void SetLowMemoryMargin(int64 margin_mb);
-
  private:
-  scoped_refptr<LowMemoryObserverImpl> observer_;
+  // Callback from LowMemoryListenerImpl when memory is low. Called on the UI
+  // thread.
+  void OnMemoryLow();
+
+  scoped_refptr<LowMemoryListenerImpl> observer_;
+  LowMemoryListenerDelegate* delegate_;
+  base::WeakPtrFactory<LowMemoryListener> weak_factory_;
 
-  DISALLOW_COPY_AND_ASSIGN(LowMemoryObserver);
+  DISALLOW_COPY_AND_ASSIGN(LowMemoryListener);
 };
 
 }  // namespace chromeos
 
-#endif  // CHROME_BROWSER_CHROMEOS_MEMORY_LOW_MEMORY_OBSERVER_H_
+#endif  // CHROMEOS_MEMORY_LOW_MEMORY_LISTENER_H_