Adding show profile switcher field trial.

chrome/browser/chrome_browser_field_trials.cc

Index: chrome/browser/chrome_browser_field_trials.cc
diff --git a/chrome/browser/chrome_browser_field_trials.cc b/chrome/browser/chrome_browser_field_trials.cc
index 05be70118dfc9ee8a7c3b3513c084ba88755052e..5d35cc0b4aaa4f3330056d3f26fed0483f1c4fbd 100644
--- a/chrome/browser/chrome_browser_field_trials.cc
+++ b/chrome/browser/chrome_browser_field_trials.cc
@@ -19,6 +19,7 @@
 #include "chrome/browser/gpu/chrome_gpu_util.h"
 #include "chrome/browser/metrics/variations/variations_service.h"
 #include "chrome/browser/prerender/prerender_field_trial.h"
+#include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/safe_browsing/safe_browsing_blocking_page.h"
 #include "chrome/browser/ui/sync/one_click_signin_helper.h"
 #include "chrome/common/chrome_switches.h"
@@ -145,6 +146,7 @@ void ChromeBrowserFieldTrials::SetupFieldTrials(
   DisableNewTabFieldTrialIfNecesssary();
   SetUpInfiniteCacheFieldTrial();
   SetUpCacheSensitivityAnalysisFieldTrial();
+  DisableShowProfileSwitcherTrialIfNecessary();
   WindowsOverlappedTCPReadsFieldTrial();
 #if defined(ENABLE_ONE_CLICK_SIGNIN)
   OneClickSigninHelper::InitializeFieldTrial();
@@ -297,6 +299,14 @@ void ChromeBrowserFieldTrials::SetUpInfiniteCacheFieldTrial() {
   trial->AppendGroup("Control", infinite_cache_probability);
 }
 
+void ChromeBrowserFieldTrials::DisableShowProfileSwitcherTrialIfNecessary() {
+  // This trial is created by the VariationsService, but it needs to be disabled
+  // if multi-profiles isn't enabled.
+  base::FieldTrial* trial = base::FieldTrialList::Find("ShowProfileSwitcher");
+  if (trial && !ProfileManager::IsMultipleProfilesEnabled())
+    trial->Disable();
+}
+
 void ChromeBrowserFieldTrials::SetUpCacheSensitivityAnalysisFieldTrial() {
   const base::FieldTrial::Probability kDivisor = 100;