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

public/platform/WebCrypto.h

 /*
  * Copyright (C) 2013 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 26 matching lines @@
 #include "WebPrivatePtr.h"
 #include "WebString.h"
 #include "WebVector.h"
 
 namespace WebCore { class CryptoResult; }
 
 #if INSIDE_BLINK
 namespace WTF { template <typename T> class PassRefPtr; }
 #endif
 
+// FIXME: Remove once chromium side rolls.
+#define WEBCRYPTO_RESULT_HAS_CANCELLED 1
+
 namespace blink {
 
 class WebArrayBuffer;
 class WebString;
 
 enum WebCryptoErrorType {
     WebCryptoErrorTypeType,
     WebCryptoErrorTypeNotSupported,
     WebCryptoErrorTypeSyntax,
     WebCryptoErrorTypeInvalidState,
@@ skipping 31 matching lines @@
 
     // Note that WebArrayBuffer is NOT safe to create from another thread.
     BLINK_PLATFORM_EXPORT void completeWithBuffer(const WebArrayBuffer&);
     // Makes a copy of the input data given as a pointer and byte length.
     BLINK_PLATFORM_EXPORT void completeWithBuffer(const void*, unsigned);
     BLINK_PLATFORM_EXPORT void completeWithJson(const char* utf8Data, unsigned length);
     BLINK_PLATFORM_EXPORT void completeWithBoolean(bool);
     BLINK_PLATFORM_EXPORT void completeWithKey(const WebCryptoKey&);
     BLINK_PLATFORM_EXPORT void completeWithKeyPair(const WebCryptoKey& publicKey, const WebCryptoKey& privateKey);
 
+    // Returns true if the underlying operation was cancelled.
+    // This method can be called from any thread.
+    BLINK_PLATFORM_EXPORT bool cancelled() const;
+
 #if INSIDE_BLINK
     BLINK_PLATFORM_EXPORT explicit WebCryptoResult(const WTF::PassRefPtr<WebCore::CryptoResult>&);
 #endif
 
 private:
     BLINK_PLATFORM_EXPORT void reset();
     BLINK_PLATFORM_EXPORT void assign(const WebCryptoResult&);
 
     WebPrivatePtr<WebCore::CryptoResult> m_impl;
 };
@@ skipping 31 matching lines @@
     // Implementations signal completion by calling one of the methods on
     // "result". Only a single result/error should be set for the request.
     // Different operations expect different result types based on the
     // algorithm parameters; see the Web Crypto standard for details.
     //
     // The result can be set either synchronously while handling the request,
     // or asynchronously after the method has returned. When completing
     // asynchronously make a copy of the WebCryptoResult and call it from the
     // same thread that started the request.
     //
+    // If the request was cancelled it is not necessary for implementations to
+    // set the result.
+    //
     // -----------------------
     // Threading
     // -----------------------
     //
     // The WebCrypto interface will be called from blink threads (main or
     // web worker). All communication back to Blink must be on this same thread.
     //
     // Notably:
     //
     //   * The WebCryptoResult can be copied between threads, however all
@@ skipping 108 matching lines @@
     // Returns true on success.
     virtual bool serializeKeyForClone(const WebCryptoKey&, WebVector<unsigned char>&) { return false; }
 
 protected:
     virtual ~WebCrypto() { }
 };
 
 } // namespace blink
 
 #endif