Add Ignition to about:flags.

gin/v8_initializer.cc

Index: gin/v8_initializer.cc
diff --git a/gin/v8_initializer.cc b/gin/v8_initializer.cc
index 117723eac99ca20729fe7d572f94ea711eca7c67..41e34e865675bb77d01a207c5533a7a54aeaa42a 100644
--- a/gin/v8_initializer.cc
+++ b/gin/v8_initializer.cc
@@ -10,6 +10,7 @@
 #include <memory>
 
 #include "base/debug/alias.h"
+#include "base/feature_list.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/memory_mapped_file.h"
@@ -21,6 +22,7 @@
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
 #include "crypto/sha2.h"
+#include "gin/public/gin_features.h"
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
 #if defined(OS_ANDROID)
@@ -421,6 +423,11 @@ void V8Initializer::Initialize(IsolateHolder::ScriptMode mode,
     v8::V8::SetFlagsFromString(flag, sizeof(flag) - 1);
   }
 
+  if (base::FeatureList::IsEnabled(features::kV8Ignition)) {
+    std::string flag("--ignition");
+    v8::V8::SetFlagsFromString(flag.c_str(), static_cast<int>(flag.size()));
+  }
+
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
   v8::StartupData natives;
   natives.data = reinterpret_cast<const char*>(g_mapped_natives->data());