Add a base::Feature to change progress bar completion policy.

content/common/content_switches_internal.cc

Index: content/common/content_switches_internal.cc
diff --git a/content/common/content_switches_internal.cc b/content/common/content_switches_internal.cc
index eeb18a7603b40c6987a33bbfe248b5fe2591a163..a2a6674fd7c75bd639d928ea5cfca2c6518ac47c 100644
--- a/content/common/content_switches_internal.cc
+++ b/content/common/content_switches_internal.cc
@@ -36,6 +36,12 @@ bool IsUseZoomForDSFEnabledByDefault() {
 #endif
 }
 
+#if defined(ANDROID)
+const base::Feature kProgressBarCompletionResourcesBeforeDOMContentLoaded{

[Charlie Reis, 2016/10/21 22:07:20]

nit: Is there room for a space before the brace, as above?

[Nate Chapin, 2016/10/21 22:09:22]

Yep, will fix before landing.

+    "progress-bar-completion-resources-before-domContentLoaded",
+    base::FEATURE_DISABLED_BY_DEFAULT};
+#endif
+
 }  // namespace
 
 bool IsPinchToZoomEnabled() {
@@ -106,6 +112,12 @@ ProgressBarCompletion GetProgressBarCompletionPolicy() {
       "resourcesBeforeDOMContentLoadedAndSameOriginIframes") {
     return ProgressBarCompletion::RESOURCES_BEFORE_DCL_AND_SAME_ORIGIN_IFRAMES;
   }
+  // The command line, which is set by the user, takes priority. Otherwise,
+  // fall back to the feature flag.
+  if (base::FeatureList::IsEnabled(
+          kProgressBarCompletionResourcesBeforeDOMContentLoaded)) {
+    return ProgressBarCompletion::RESOURCES_BEFORE_DCL;
+  }
 #endif
   return ProgressBarCompletion::LOAD_EVENT;
 }