Add a field trial to enable out-of-process V8 pac.

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 8c9eee73eccca5d6d3988ee4eaa8c5fc95af419f..2102c36545456fb14deee305be2bcded91b7b9a7 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -500,6 +500,16 @@ const Experiment::Choice kSupervisedUserSafeSitesChoices[] = {
     "online-check-only" }
 };
 
+const Experiment::Choice kV8PacChoices[] = {
+  { IDS_GENERIC_EXPERIMENT_CHOICE_DEFAULT, "", "" },
+  { IDS_GENERIC_EXPERIMENT_CHOICE_ENABLED,
+    switches::kV8PacMojoOutOfProcess,
+    "enabled" },
+  { IDS_GENERIC_EXPERIMENT_CHOICE_DISABLED,
+    switches::kDisableOutOfProcessPac,
+    "disabled" }
+};
+
 // RECORDING USER METRICS FOR FLAGS:
 // -----------------------------------------------------------------------------
 // The first line of the experiment is the internal name. If you'd like to
@@ -2333,7 +2343,7 @@ const Experiment kExperiments[] = {
     IDS_FLAGS_V8_PAC_MOJO_OUT_OF_PROCESS_NAME,
     IDS_FLAGS_V8_PAC_MOJO_OUT_OF_PROCESS_DESCRIPTION,
     kOsDesktop,
-    SINGLE_VALUE_TYPE(switches::kV8PacMojoOutOfProcess),
+    MULTI_VALUE_TYPE(kV8PacChoices),

[Alexei Svitkine (slow), 2015/05/15 14:33:42]

Nit: Use ENABLE_DISABLE_VALUE_TYPE() instead.

[Anand Mistry (off Chromium), 2015/05/15 18:47:58]

Done.

   },
 #if defined(ENABLE_MEDIA_ROUTER)
   {