Add documentation for MemoryCoordinator-related primitives

base/memory/memory_pressure_listener.h

Index: base/memory/memory_pressure_listener.h
diff --git a/base/memory/memory_pressure_listener.h b/base/memory/memory_pressure_listener.h
index 7e97010085dc8dcaea7f0fb68993b968fc5484c5..feff26a796465d2a6766e660e0f0645edb7c779e 100644
--- a/base/memory/memory_pressure_listener.h
+++ b/base/memory/memory_pressure_listener.h
@@ -43,6 +43,9 @@ namespace base {
 //    // Stop listening.
 //    delete my_listener;
 //
+// NOTE: The MemoryPressureListener is in the process of being replaced
+// with the MemoryCoordinator. See //base/memory/memory_coordinator.md
+// for more details.

[Ryan Sleevi, 2017/02/25 02:57:10]

Suggestion: Update line 5 with something like: 

// This file contains a set of APIs for receiving notifications of
// memory pressure events, where supported by the underlying platform.
// Developers should strive to reduce non-essential memory when
// receiving these notifications, when possible.
//
// For further details, see //base/memory/memory_coordinator.md for
// further details


Then update this with:
// NOTE: MemoryPressureListener is in the process of being deprecated. See
//base/memory/memory_coordinator.md for current best practices to respond to
memory pressure events.

 class BASE_EXPORT MemoryPressureListener {
  public:
   // A Java counterpart will be generated for this enum.