Add memory pressure interrupt for memory pressure notification

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 5857 matching lines @@
    * Request V8 to interrupt long running JavaScript code and invoke
    * the given |callback| passing the given |data| to it. After |callback|
    * returns control will be returned to the JavaScript code.
    * There may be a number of interrupt requests in flight.
    * Can be called from another thread without acquiring a |Locker|.
    * Registered |callback| must not reenter interrupted Isolate.
    */
   void RequestInterrupt(InterruptCallback callback, void* data);
 
   /**
+   * Request V8 to interrupt long running JavaScript code and do GC,
+   * when system memory is pressured.
+   */
+  void RequestMemoryPressureInterrupt();

[jochen (gone - plz use gerrit), 2016/03/09 15:18:59]

I'd prefer an API ReportMemoryPressure(level) where level is an enum class
MemoryPressureLevel { kNone, kModerate, kCritical}

internally, we could just clear the interrupt request for none and do a low
memory gc for moderate / critical

+
+  /**
    * Request garbage collection in this Isolate. It is only valid to call this
    * function if --expose_gc was specified.
    *
    * This should only be used for testing purposes and not to enforce a garbage
    * collection schedule. It has strong negative impact on the garbage
    * collection performance. Use IdleNotificationDeadline() or
    * LowMemoryNotification() instead to influence the garbage collection
    * schedule.
    */
   void RequestGarbageCollectionForTesting(GarbageCollectionType type);
@@ skipping 132 matching lines @@
   V8_DEPRECATED("use IdleNotificationDeadline()",
                 bool IdleNotification(int idle_time_in_ms));
 
   /**
    * Optional notification that the system is running low on memory.
    * V8 uses these notifications to attempt to free memory.
    */
   void LowMemoryNotification();
 
   /**
+   * Optional notification that memory pressure interrupt is requested.
+   * V8 uses these notifications to attempt to free memory.
+   */
+  void GCNotificationBasedOnMemoryPressureInterrupt();

[jochen (gone - plz use gerrit), 2016/03/09 15:18:59]

that shouldn't be required

+
+  /**
    * Optional notification that a context has been disposed. V8 uses
    * these notifications to guide the GC heuristic. Returns the number
    * of context disposals - including this one - since the last time
    * V8 had a chance to clean up.
    *
    * The optional parameter |dependant_context| specifies whether the disposed
    * context was depending on state from other contexts or not.
    */
   int ContextDisposedNotification(bool dependant_context = true);
 
@@ skipping 2618 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // INCLUDE_V8_H_