Add a command line option and a Finch experiment for script streaming.

content/browser/renderer_host/render_view_host_impl.cc

Index: content/browser/renderer_host/render_view_host_impl.cc
diff --git a/content/browser/renderer_host/render_view_host_impl.cc b/content/browser/renderer_host/render_view_host_impl.cc
index 1068d220368110fb7f24868701df7db93679c9f4..eac9a23f996541418ceed12e3553bdb4add8d9c1 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -15,6 +15,7 @@
 #include "base/i18n/rtl.h"
 #include "base/json/json_reader.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
@@ -476,6 +477,10 @@ WebPreferences RenderViewHostImpl::ComputeWebkitPrefs(const GURL& url) {
     }
   }
 
+  prefs.v8_script_streaming_enabled =
+      command_line.HasSwitch(switches::kEnableV8ScriptStreaming) ||
+      base::FieldTrialList::FindFullName("V8ScriptStreaming") == "Enabled";
+
   GetContentClient()->browser()->OverrideWebkitPrefs(this, url, &prefs);
   return prefs;
 }