Do V8 GC ASAP if system memory is pressured[reland]

third_party/WebKit/public/web/WebKit.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebKit_h
 #define WebKit_h
 
 #include "../platform/Platform.h"
 
 namespace v8 {
 class Isolate;
+enum class MemoryPressureLevel;
 }
 
 namespace blink {
 
 // Initialize the entire Blink (wtf, platform, core, modules and web).
 // If you just need wtf and platform, use Platform::initialize instead.
 //
 // Must be called on the thread that will be the main thread before
 // using any other public APIs. The provided Platform; must be
 // non-null and must remain valid until the current thread calls shutdown.
@@ skipping 29 matching lines @@
 BLINK_EXPORT void enableLogChannel(const char*);
 
 // Purge the plugin list cache. If |reloadPages| is true, any pages
 // containing plugins will be reloaded after refreshing the plugin list.
 BLINK_EXPORT void resetPluginCache(bool reloadPages = false);
 
 // The embedder should call this periodically in an attempt to balance overall
 // performance and memory usage.
 BLINK_EXPORT void decommitFreeableMemory();
 
+// Send memory pressure notification to worker thread isolate.
+BLINK_EXPORT void MemoryPressureNotificationToWorkerThreadIsolates(
+    v8::MemoryPressureLevel);
+
 } // namespace blink
 
 #endif