Add digestSynchronous WebCrypto method.

public/platform/WebCrypto.h

Index: public/platform/WebCrypto.h
diff --git a/public/platform/WebCrypto.h b/public/platform/WebCrypto.h
index 998a2153ec8165ddf0a17896085ff8d2873a2920..0d6f1cfa742cc03db0d8ae941a000c84626b46fe 100644
--- a/public/platform/WebCrypto.h
+++ b/public/platform/WebCrypto.h
@@ -178,6 +178,15 @@ public:
     // It is possible that unwrappedKeyAlgorithm.isNull()
     virtual void unwrapKey(WebCryptoKeyFormat, const unsigned char* wrappedKey, unsigned wrappedKeySize, const WebCryptoKey&, const WebCryptoAlgorithm& unwrapAlgorithm, const WebCryptoAlgorithm& unwrappedKeyAlgorithm, bool extractable, WebCryptoKeyUsageMask, WebCryptoResult result) { result.completeWithError(); }
 
+    // This is the one exception to the "Completeing the request" guarantees

[eroman, 2014/02/08 00:03:40]

typo completing

[jww, 2014/02/08 00:41:55]

Done.

+    // outlined above. digestSynchronous must provide the result synchronously.
+    // Consumers may assume that the result object will have one of its
+    // "complete" functions called before digestSynchronous returns.
+    //
+    // This is useful for Blink internal crypto and is not part of the
+    // WebCrypto standard.
+    virtual void digestSynchronous(const WebCryptoAlgorithm&, const unsigned char* data, unsigned dataSize, WebCryptoResult result) { result.completeWithError(); }

[eroman, 2014/02/08 00:03:40]

Is it going to be convenient enough having "WebCryptoResult" here? This mean
clients will have to provide their own implementation to extract the result.

What about having the return value be a boolean for success, and the input be a
vector

[jww, 2014/02/08 00:41:55]

That works for me. I was trying to keep the API similar to the other methods,
but I suppose there's no reason for that.

+
 protected:
     virtual ~WebCrypto() { }
 };