Remove support for the keygen tag

third_party/WebKit/public/platform/Platform.h

Index: third_party/WebKit/public/platform/Platform.h
diff --git a/third_party/WebKit/public/platform/Platform.h b/third_party/WebKit/public/platform/Platform.h
index e8e786ffcf145627955cdb4bc791ca4cebfaca5c..46ecf88d0d212c765bed02cf4055a75b7ef21ed6 100644
--- a/third_party/WebKit/public/platform/Platform.h
+++ b/third_party/WebKit/public/platform/Platform.h
@@ -290,20 +290,6 @@ class BLINK_PLATFORM_EXPORT Platform {
   // hash must have been generated by calling VisitedLinkHash().
   virtual bool isLinkVisited(unsigned long long linkHash) { return false; }
 
-  // Keygen --------------------------------------------------------------
-
-  // Handle the <keygen> tag for generating client certificates
-  // Returns a base64 encoded signed copy of a public key from a newly
-  // generated key pair and the supplied challenge string. keySizeindex
-  // specifies the strength of the key.
-  virtual WebString signedPublicKeyAndChallengeString(
-      unsigned keySizeIndex,
-      const WebString& challenge,
-      const WebURL& url,
-      const WebURL& topOrigin) {
-    return WebString();
-  }
-
   // Same as above, but always returns actual value, without any caches.
   virtual size_t actualMemoryUsageMB() { return 0; }