Introduce KeepAliveWhilePending to ScriptPromiseResolverWithContext.

Source/modules/crypto/SubtleCrypto.h

Index: Source/modules/crypto/SubtleCrypto.h
diff --git a/Source/modules/crypto/SubtleCrypto.h b/Source/modules/crypto/SubtleCrypto.h
index ad7f201c043f76eb9a9b1d884921316d1bad2fd6..60c57b2d6c80ebcc348b2b9561b2229b1ea83abf 100644
--- a/Source/modules/crypto/SubtleCrypto.h
+++ b/Source/modules/crypto/SubtleCrypto.h
@@ -33,10 +33,11 @@
 
 #include "bindings/v8/ScriptPromise.h"
 #include "bindings/v8/ScriptWrappable.h"
+#include "modules/crypto/CrossThreadCryptoResult.h"
 #include "platform/heap/Handle.h"
+#include "public/platform/WebCryptoAlgorithm.h"
 #include "wtf/ArrayPiece.h"
 #include "wtf/Forward.h"
-#include "wtf/RefCounted.h"
 
 namespace WebCore {
 
@@ -49,6 +50,7 @@ public:
     {
         return new SubtleCrypto();
     }
+    virtual ~SubtleCrypto();
 
     ScriptPromise encrypt(ScriptState*, const Dictionary&, Key*, const ArrayPiece&);
     ScriptPromise decrypt(ScriptState*, const Dictionary&, Key*, const ArrayPiece&);
@@ -64,10 +66,15 @@ public:
     ScriptPromise wrapKey(ScriptState*, const String&, Key*, Key*, const Dictionary&);
     ScriptPromise unwrapKey(ScriptState*, const String&, const ArrayPiece&, Key*, const Dictionary&, const Dictionary&, bool, const Vector<String>&);
 
-    void trace(Visitor*) { }
+    void trace(Visitor*);
 
 private:
+    class PendingResult;
     SubtleCrypto();
+
+    ScriptPromise startCryptoOperation(ScriptState*, const Dictionary&, Key*, blink::WebCryptoOperation, const ArrayPiece& signature, const ArrayPiece& dataBuffer);
+    PassRefPtr<CrossThreadCryptoResult<PendingResult> > createCrossThreadCryptoResult(ScriptState*, ScriptPromise*);
+    HeapHashSet<Member<PendingResult> > m_pendingResults;
 };
 
 } // namespace WebCore