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

third_party/WebKit/public/web/WebKit.h

Index: third_party/WebKit/public/web/WebKit.h
diff --git a/third_party/WebKit/public/web/WebKit.h b/third_party/WebKit/public/web/WebKit.h
index 0ee53fd2cc2cd9d50146bc1095a704d84adce1d1..d483405287972c99c2c59c453d3e4736091eebe2 100644
--- a/third_party/WebKit/public/web/WebKit.h
+++ b/third_party/WebKit/public/web/WebKit.h
@@ -35,6 +35,7 @@
 
 namespace v8 {
 class Isolate;
+enum class MemoryPressureLevel;
 }
 
 namespace blink {
@@ -84,6 +85,10 @@ BLINK_EXPORT void resetPluginCache(bool reloadPages = false);
 // 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