Gather metrics classifying the cause of the TLS fallback.

net/socket/client_socket_handle.cc

Index: net/socket/client_socket_handle.cc
diff --git a/net/socket/client_socket_handle.cc b/net/socket/client_socket_handle.cc
index 734e58aeffff7369f6547ec84a98d8307d10d26e..75729cb152afc09ba7ee24d25a695422bbb9ef3e 100644
--- a/net/socket/client_socket_handle.cc
+++ b/net/socket/client_socket_handle.cc
@@ -21,7 +21,9 @@ ClientSocketHandle::ClientSocketHandle()
       reuse_type_(ClientSocketHandle::UNUSED),
       callback_(base::Bind(&ClientSocketHandle::OnIOComplete,
                            base::Unretained(this))),
-      is_ssl_error_(false) {}
+      is_ssl_error_(false),
+      ssl_failure_state_(kSSLFailureNone) {
+}
 
 ClientSocketHandle::~ClientSocketHandle() {
   Reset();
@@ -72,6 +74,7 @@ void ClientSocketHandle::ResetInternal(bool cancel) {
 void ClientSocketHandle::ResetErrorState() {
   is_ssl_error_ = false;
   ssl_error_response_info_ = HttpResponseInfo();
+  ssl_failure_state_ = kSSLFailureNone;
   pending_http_proxy_connection_.reset();
 }