Add flag to override Effective Connection Type

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index 4e730e6c6f346b79c4749d51b6e70b3114fbb0ec..e79b83a422abc1352425af6eb565b34e2a054f0c 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -91,6 +91,7 @@
 #include "net/net_features.h"
 #include "net/nqe/external_estimate_provider.h"
 #include "net/nqe/network_quality_estimator.h"
+#include "net/nqe/network_quality_estimator_params.h"
 #include "net/proxy/proxy_config_service.h"
 #include "net/proxy/proxy_script_fetcher_impl.h"
 #include "net/proxy/proxy_service.h"
@@ -560,6 +561,19 @@ void IOThread::Init() {
   variations::GetVariationParams(kNetworkQualityEstimatorFieldTrialName,
                                  &network_quality_estimator_params);
 
+  if (command_line.HasSwitch(switches::kForceEffectiveConnectionType)) {
+    const std::string force_ect_value =
+        base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+            switches::kForceEffectiveConnectionType);
+
+    if (!force_ect_value.empty()) {
+      // If the effective connection type is forced using command line switch,
+      // it overrides the one set by field trial.
+      network_quality_estimator_params[net::kForceEffectiveConnectionType] =
+          force_ect_value;
+    }
+  }

[mmenke, 2017/05/02 16:09:43]

Not going to block on this, but for network stack servification, I suspect we'll
want a C++ API here, rather than sending a bunch of key/value string pairs that
are parsed in net/.

+
   std::unique_ptr<net::ExternalEstimateProvider> external_estimate_provider;
 #if defined(OS_ANDROID)
   external_estimate_provider.reset(