Support for the new WebCrypto digest by chunks API.

content/child/webcrypto/platform_crypto.h

Index: content/child/webcrypto/platform_crypto.h
diff --git a/content/child/webcrypto/platform_crypto.h b/content/child/webcrypto/platform_crypto.h
index 8c28e3f02b9058427f474f89f38b8ae6a4f8e72e..fa5ac9ff3b0c2491ddbaeafdec09c155a8a69771 100644
--- a/content/child/webcrypto/platform_crypto.h
+++ b/content/child/webcrypto/platform_crypto.h
@@ -7,6 +7,7 @@
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
 #include "third_party/WebKit/public/platform/WebArrayBuffer.h"
 #include "third_party/WebKit/public/platform/WebCrypto.h"
 #include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
@@ -92,6 +93,11 @@ Status DigestSha(blink::WebCryptoAlgorithmId algorithm,
                  blink::WebArrayBuffer* buffer);
 
 // Preconditions:
+//  * |algorithm| is a SHA function.
+scoped_ptr<blink::WebCryptoDigestor> CreateDigestor(
+    blink::WebCryptoAlgorithmId algorithm);
+
+// Preconditions:
 //  * |key| is non-null.
 //  * |hash| is a digest algorithm.
 Status SignRsaSsaPkcs1v1_5(PrivateKey* key,