Make memory pressure notifier configurable

base/memory/memory_pressure_monitor.h

Index: base/memory/memory_pressure_monitor.h
diff --git a/base/memory/memory_pressure_monitor.h b/base/memory/memory_pressure_monitor.h
index 6073bd3f44ca8f26b953a31967406c747e35bb58..f345b6738b9190d0541bf7ef646e7269029e0c91 100644
--- a/base/memory/memory_pressure_monitor.h
+++ b/base/memory/memory_pressure_monitor.h
@@ -23,6 +23,7 @@ namespace base {
 class BASE_EXPORT MemoryPressureMonitor {
  public:
   using MemoryPressureLevel = base::MemoryPressureListener::MemoryPressureLevel;
+  using DispatchCallback = void(*)(MemoryPressureLevel level);

[danakj, 2016/07/08 00:03:53]

oh I was expecting a base::Callback, but if you don't need that for the new
thing then this is fine too.

[bashi, 2016/07/08 00:13:05]

Ah, good point. I have a WIP CL locally and a function pointer is enough for the
CL, but I noticed that it would need to be a callback after some changes. I'll
change DispatchCallback to a base::Callback.

 
   virtual ~MemoryPressureMonitor();
 
@@ -32,6 +33,10 @@ class BASE_EXPORT MemoryPressureMonitor {
   // Returns the currently observed memory pressure.
   virtual MemoryPressureLevel GetCurrentPressureLevel() const = 0;
 
+  // Sets a notification callback. The default callback invokes
+  // base::MemoryPressureListener::NotifyMemoryPressure.
+  virtual void SetDispatchCallback(DispatchCallback callback) = 0;
+
  protected:
   MemoryPressureMonitor();