Add a new gyp flag: fieldtrial_testing_like_official_build

chrome/browser/chrome_browser_main.cc

Index: chrome/browser/chrome_browser_main.cc
diff --git a/chrome/browser/chrome_browser_main.cc b/chrome/browser/chrome_browser_main.cc
index d80d4e405e7125cde7d6608bc80c32e8a0b99053..2c121fe6ea3cc8ab19cac4e830324a2f44cf4a3e 100644
--- a/chrome/browser/chrome_browser_main.cc
+++ b/chrome/browser/chrome_browser_main.cc
@@ -635,12 +635,12 @@ void ChromeBrowserMainParts::SetupMetricsAndFieldTrials() {
                   << " list specified.";
   }
 
-#if !defined(GOOGLE_CHROME_BUILD)
+#if defined(FIELDTRIAL_TESTING_ENABLED)
   if (!command_line->HasSwitch(switches::kDisableFieldTrialTestingConfig) &&
       !command_line->HasSwitch(switches::kForceFieldTrials) &&
       !command_line->HasSwitch(switches::kVariationsServerURL))
     chrome_variations::AssociateDefaultFieldTrialConfig();
-#endif  // !defined(GOOGLE_CHROME_BUILD)
+#endif  // defined(FIELDTRIAL_TESTING_ENABLED)
 
   if (command_line->HasSwitch(switches::kForceVariationIds)) {
     // Create default variation ids which will always be included in the