Added command line flag to override list of proxies from Data Saver API

components/data_reduction_proxy/core/common/data_reduction_proxy_params_unittest.cc

Index: components/data_reduction_proxy/core/common/data_reduction_proxy_params_unittest.cc
diff --git a/components/data_reduction_proxy/core/common/data_reduction_proxy_params_unittest.cc b/components/data_reduction_proxy/core/common/data_reduction_proxy_params_unittest.cc
index e4234254894c48136779e9022240f4635c4988ec..d4870ae7e97a8c334e92fcd262b7525e174c0b54 100644
--- a/components/data_reduction_proxy/core/common/data_reduction_proxy_params_unittest.cc
+++ b/components/data_reduction_proxy/core/common/data_reduction_proxy_params_unittest.cc
@@ -423,4 +423,20 @@ TEST_F(DataReductionProxyParamsTest, GetConfigServiceURL) {
   }
 }
 
+TEST(DataReductionProxyParamsStandaloneTest, OverrideProxiesForHttp) {
+  base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
+      switches::kDataReductionProxyHttpProxies,
+      "http://override-first.net;http://override-second.net");
+  DataReductionProxyParams params(
+      DataReductionProxyParams::kAllowAllProxyConfigurations);
+
+  std::vector<net::ProxyServer> expected_override_proxies_for_http;
+  expected_override_proxies_for_http.push_back(net::ProxyServer::FromURI(
+      "http://override-first.net", net::ProxyServer::SCHEME_HTTP));
+  expected_override_proxies_for_http.push_back(net::ProxyServer::FromURI(
+      "http://override-second.net", net::ProxyServer::SCHEME_HTTP));
+
+  EXPECT_EQ(expected_override_proxies_for_http, params.proxies_for_http());
+}
+
 }  // namespace data_reduction_proxy