Implement crypto signature verification routines using OpenSSL.

extensions/extensions.gyp

Index: extensions/extensions.gyp
diff --git a/extensions/extensions.gyp b/extensions/extensions.gyp
index 46a2b698ad5f504dd688d37ff88634ad142af4b4..3a8a257f592feb707356179776ca884e67a8422f 100644
--- a/extensions/extensions.gyp
+++ b/extensions/extensions.gyp
@@ -1249,6 +1249,11 @@
             '../base/allocator/allocator.gyp:allocator',
           ],
         }],
+        ['use_openssl==1', {
+          'sources': [
+            'browser/api/cast_channel/cast_auth_util_openssl_unittest.cc',
+          ]
+        }],
       ],
     },
   ]