Introduce new API for detecting when the embedder is in foreground/background.

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.
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    * 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);
 
   /**
+   * Optional notification that the isolate switched to the foreground.
+   * V8 uses these notifications to guide heuristics.
+   */
+  void IsolateInForegroundNotification();
+
+  /**
+   * Optional notification that the isolate switched to the background.
+   * V8 uses these notifications to guide heuristics.
+   */
+  void IsolateInBackgroundNotification();
+
+  /**
    * Allows the host application to provide the address of a function that is
    * notified each time code is added, moved or removed.
    *
    * \param options options for the JIT code event handler.
    * \param event_handler the JIT code event handler, which will be invoked
    *     each time code is added, moved or removed.
    * \note \p event_handler won't get notified of existent code.
    * \note since code removal notifications are not currently issued, the
    *     \p event_handler may get notifications of code that overlaps earlier
    *     code notifications. This happens when code areas are reused, and the
@@ skipping 2564 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_