[webcrypto] Allow crypto operations to be cancelled by the platform implementation.

Source/modules/crypto/CryptoResultImpl.cpp

Index: Source/modules/crypto/CryptoResultImpl.cpp
diff --git a/Source/modules/crypto/CryptoResultImpl.cpp b/Source/modules/crypto/CryptoResultImpl.cpp
index e2d4f9edc5497be693b8a6d4db6f7190f9b56955..92891da37bba93b6a8a6f57a12f095382a0551bc 100644
--- a/Source/modules/crypto/CryptoResultImpl.cpp
+++ b/Source/modules/crypto/CryptoResultImpl.cpp
@@ -47,27 +47,30 @@
 
 namespace WebCore {
 
-namespace {
-
-class WeakResolver : public ScriptPromiseResolverWithContext {
+class CryptoResultImpl::WeakResolver : public ScriptPromiseResolverWithContext {
 public:
-    static WeakPtr<ScriptPromiseResolverWithContext> create(ScriptState* scriptState)
+    static WeakPtr<ScriptPromiseResolverWithContext> create(ScriptState* scriptState, CryptoResultImpl* result)
     {
-        RefPtr<WeakResolver> p = adoptRef(new WeakResolver(scriptState));
+        RefPtr<WeakResolver> p = adoptRef(new WeakResolver(scriptState, result));
         p->suspendIfNeeded();
         p->keepAliveWhilePending();
         return p->m_weakPtrFactory.createWeakPtr();
     }
 
+    virtual ~WeakResolver()
+    {
+        m_result->cancel();
+    }
+
 private:
-    explicit WeakResolver(ScriptState* scriptState)
+    WeakResolver(ScriptState* scriptState, CryptoResultImpl* result)
         : ScriptPromiseResolverWithContext(scriptState)
-        , m_weakPtrFactory(this) { }
+        , m_weakPtrFactory(this)
+        , m_result(result) { }
     WeakPtrFactory<ScriptPromiseResolverWithContext> m_weakPtrFactory;
+    RefPtr<CryptoResultImpl> m_result;
 };
 
-} // namespace
-
 ExceptionCode webCryptoErrorToExceptionCode(blink::WebCryptoErrorType errorType)
 {
     switch (errorType) {
@@ -155,8 +158,19 @@ void CryptoResultImpl::completeWithKeyPair(const blink::WebCryptoKey& publicKey,
         m_resolver->resolve(KeyPair::create(publicKey, privateKey));
 }
 
+bool CryptoResultImpl::cancelled() const
+{
+    return acquireLoad(&m_cancelled);
+}
+
+void CryptoResultImpl::cancel()
+{
+    releaseStore(&m_cancelled, 1);
+}
+
 CryptoResultImpl::CryptoResultImpl(ScriptState* scriptState)
-    : m_resolver(WeakResolver::create(scriptState))
+    : m_resolver(WeakResolver::create(scriptState, this))
+    , m_cancelled(0)
 {
 }