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

components/data_reduction_proxy/core/browser/data_reduction_proxy_mutable_config_values.cc

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_mutable_config_values.cc
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_mutable_config_values.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_mutable_config_values.cc
index 5ba7a4f574b9a5b6c5c66804be7739d2d23c3f96..01a9de7d4d9b975754b7e5d1cd60d67646b00ec4 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_mutable_config_values.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_mutable_config_values.cc
@@ -4,7 +4,13 @@
 
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_mutable_config_values.h"
 
+#include <string>
+#include <vector>
+
+#include "base/command_line.h"
+#include "base/strings/string_split.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_params.h"
+#include "components/data_reduction_proxy/core/common/data_reduction_proxy_switches.h"
 
 namespace data_reduction_proxy {
 
@@ -25,7 +31,22 @@ DataReductionProxyMutableConfigValues::DataReductionProxyMutableConfigValues()
     : promo_allowed_(false),
       holdback_(false),
       allowed_(false),
-      fallback_allowed_(false) {
+      fallback_allowed_(false),
+      use_override_proxies_for_http_(false) {
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDataReductionProxyConfigHttpProxiesOverride)) {
+    use_override_proxies_for_http_ = true;
+    std::string proxy_overrides =
+        base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+            switches::kDataReductionProxyConfigHttpProxiesOverride);
+    std::vector<std::string> proxy_override_values = base::SplitString(
+        proxy_overrides, ";", base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
+    for (const std::string& proxy_override : proxy_override_values) {
+      override_proxies_for_http_.push_back(net::ProxyServer::FromURI(

[bengr, 2015/09/17 17:27:33]

What happens if the string is not a valid proxy URI?

[sclittle, 2015/09/22 19:01:59]

Then an empty invalid net::ProxyServer() will be returned and either ignored or
treated as DIRECT. It's a command line flag, so I'm not too worried about it.

+          proxy_override, net::ProxyServer::SCHEME_HTTP));
+    }
+  }
+
   // Constructed on the UI thread, but should be checked on the IO thread.
   thread_checker_.DetachFromThread();
 }
@@ -58,6 +79,13 @@ bool DataReductionProxyMutableConfigValues::UsingHTTPTunnel(
 const std::vector<net::ProxyServer>&
 DataReductionProxyMutableConfigValues::proxies_for_http() const {
   DCHECK(thread_checker_.CalledOnValidThread());
+  if (use_override_proxies_for_http_ && !proxies_for_http_.empty()) {

[bengr, 2015/09/17 17:27:34]

Do you need this separate use_override_proxies_for_http_ bool? Can you just
check if override_proxies_for_http_ is non-empty()?

[sclittle, 2015/09/22 19:01:59]

The main reason to have the bool is to allow for specifying an empty proxy list,
i.e. pretending that the Data Saver API returned an empty proxy list. It also
seems more intuitive that specifically adding the flag with an empty list will
cause Chrome to use an empty DRP proxy list. I don't mind changing this if you'd
like though.

+    // Only override the proxies if a non-empty list of proxies would have been
+    // returned otherwise. This is to prevent use of the proxies when the config
+    // has been invalidated, since attempting to use a Data Reduction Proxy
+    // without valid credentials could cause a proxy bypass.
+    return override_proxies_for_http_;
+  }
   return proxies_for_http_;
 }