Background tracing: Enable field-trial control on Android

chrome/browser/prefs/browser_prefs.cc

Index: chrome/browser/prefs/browser_prefs.cc
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 99e169ca20ef3f33fcaf0941d74872552705357e..9fa140ae915edd6ba90aecc7b22879ea05e94eb6 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -298,6 +298,7 @@ void RegisterLocalState(PrefRegistrySimple* registry) {
   browser_shutdown::RegisterPrefs(registry);
   BrowserProcessImpl::RegisterPrefs(registry);
   ChromeMetricsServiceClient::RegisterPrefs(registry);
+  ChromeTracingDelegate::RegisterPrefs(registry);
   chrome_prefs::RegisterPrefs(registry);
   variations::VariationsService::RegisterPrefs(registry);
   component_updater::RegisterPrefsForRecoveryComponent(registry);
@@ -345,7 +346,6 @@ void RegisterLocalState(PrefRegistrySimple* registry) {
 #endif
 
 #if !defined(OS_ANDROID)
-  ChromeTracingDelegate::RegisterPrefs(registry);
   RegisterBrowserPrefs(registry);
   StartupBrowserCreator::RegisterLocalStatePrefs(registry);
   // The native GCM is used on Android instead.