Add Ignition to about:flags.

chrome/renderer/chrome_render_process_observer.cc

Index: chrome/renderer/chrome_render_process_observer.cc
diff --git a/chrome/renderer/chrome_render_process_observer.cc b/chrome/renderer/chrome_render_process_observer.cc
index e8daff7e736b2f2bfc706b243a9f9d2a802cfc1a..fe532ac6f960fc55b75e44292ae52bd95b495163 100644
--- a/chrome/renderer/chrome_render_process_observer.cc
+++ b/chrome/renderer/chrome_render_process_observer.cc
@@ -27,6 +27,7 @@
 #include "base/threading/platform_thread.h"
 #include "build/build_config.h"
 #include "chrome/common/child_process_logging.h"
+#include "chrome/common/chrome_features.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/media/media_resource_provider.h"
@@ -261,6 +262,11 @@ ChromeRenderProcessObserver::ChromeRenderProcessObserver()
     v8::V8::SetFlagsFromString(flag.c_str(), static_cast<int>(flag.size()));
   }
 
+  if (base::FeatureList::IsEnabled(features::kV8Ignition)) {
+    std::string flag("--ignition");
+    v8::V8::SetFlagsFromString(flag.c_str(), static_cast<int>(flag.size()));

[jochen (gone - plz use gerrit), 2016/03/30 16:13:34]

you could move this to gin/isolate_holder.cc - then it will be applied
everywhere

[Alexei Svitkine (slow), 2016/03/30 17:02:44]

Unfortunately, this is not possible currently due to http://crbug.com/599165

I'll be working on resolving that, but for now it can't be done from there.

+  }
+
   RenderThread* thread = RenderThread::Get();
   resource_delegate_.reset(new RendererResourceDelegate());
   thread->SetResourceDispatcherDelegate(resource_delegate_.get());