[webcrypto] Make operations run on worker threads.

content/child/webcrypto/webcrypto_impl.h

Index: content/child/webcrypto/webcrypto_impl.h
diff --git a/content/child/webcrypto/webcrypto_impl.h b/content/child/webcrypto/webcrypto_impl.h
index f28cdb1a479336573f36910c92eabad64a6f3e76..a4433c1b2f761d43c11d3fe1012efa6dbee4a901 100644
--- a/content/child/webcrypto/webcrypto_impl.h
+++ b/content/child/webcrypto/webcrypto_impl.h
@@ -77,12 +77,7 @@ class WebCryptoImpl : public blink::WebCrypto {
       bool extractable,
       blink::WebCryptoKeyUsageMask usages,
       blink::WebCryptoResult result);
-  // This method synchronously computes a digest for the given data, returning
-  // |true| if successful and |false| otherwise.
-  virtual bool digestSynchronous(const blink::WebCryptoAlgorithmId algorithm_id,
-                                 const unsigned char* data,
-                                 unsigned int data_size,
-                                 blink::WebArrayBuffer& result);

[Ryan Sleevi, 2014/04/18 00:51:26]

I thought this was used by jww's SRI bits? or is that createDigestor?

[eroman, 2014/04/18 18:45:56]

We have switched all the callsites over to createDigestor() which is more
flexible (allows multi-part digest operations), so this is unused now. I am
deleting the API from the blink side, so figured I wouldn't bother updating it
for this conversion. I can split this off to a separate changelist as well if
you prefer.

[eroman, 2014/04/18 20:02:28]

Aaaand it is now deleted from Blink.

+
   // This method returns a digestor object that can be used to synchronously
   // compute a digest one chunk at a time. Thus, the consume does not need to
   // hold onto a large buffer with all the data to digest. Chunks can be given