Support generation of EC keys using P256 curve and support ECDSA certs.

talk/app/webrtc/dtlsidentitystore.cc

Index: talk/app/webrtc/dtlsidentitystore.cc
diff --git a/talk/app/webrtc/dtlsidentitystore.cc b/talk/app/webrtc/dtlsidentitystore.cc
index abd35e1fab522c47334f432bc2ccb7bba6888e17..f5b7900d8a7dc1f6bdc82799952c340e53d5d470 100644
--- a/talk/app/webrtc/dtlsidentitystore.cc
+++ b/talk/app/webrtc/dtlsidentitystore.cc
@@ -63,8 +63,8 @@ class DtlsIdentityStore::WorkerTask : public sigslot::has_slots<>,
 
  private:
   void GenerateIdentity_w() {
-    rtc::scoped_ptr<rtc::SSLIdentity> identity(
-        rtc::SSLIdentity::Generate(DtlsIdentityStore::kIdentityName));
+    rtc::scoped_ptr<rtc::SSLIdentity> identity(rtc::SSLIdentity::Generate(
+        DtlsIdentityStore::kIdentityName, rtc::KT_RSA));
 
     {
       rtc::CritScope cs(&cs_);