Merge Widevine CDM-Side Test Changes

This is a combined merge of several small test changes in the
Widevine CDM repository:

http://go/wvgerrit/11252
  Chain CreateSession() Helpers in CDM Session Unit Test

http://go/wvgerrit/10931
  Increase URLRequest timeouts and tolerate 502's.

http://go/wvgerrit/10695
  Remove dead CHROMIUM_BUILD code in engine test.

Change-Id: I75a6c9509880a20c85e54cbd2fcbf34b101ce70e

libwvdrmengine/cdm/core/test/url_request.h

@@ -17,6 +17,7 @@ class UrlRequest {
   ~UrlRequest();
 
   bool is_connected() const { return is_connected_; }
+  void Reconnect();
 
   bool PostRequest(const std::string& data);
   bool PostCertRequestInQueryString(const std::string& data);