net: disable ECDSA ciphersuites on platforms where we can't support it.

net/base/ssl_config_service.h

Index: net/base/ssl_config_service.h
diff --git a/net/base/ssl_config_service.h b/net/base/ssl_config_service.h
index de430e1472804cd23ec56f8c4aa05f7f65fafc09..82100388c7a5619b33ce83565aa4bbf24970056e 100644
--- a/net/base/ssl_config_service.h
+++ b/net/base/ssl_config_service.h
@@ -74,6 +74,9 @@ struct NET_EXPORT SSLConfig {
   // - FORTEZZA cipher suites (obsolete).
   // - IDEA cipher suites (RFC 5469 explains why).
   // - Anonymous cipher suites.
+  // - ECDSA cipher suites on platforms that do not support ECDSA signed
+  //   certificates, as servers may use the presence of such ciphersuites as a
+  //   hint to send an ECDSA certificate.
   // The ciphers listed in |disabled_cipher_suites| will be removed in addition
   // to the above list.
   //