Adding show profile switcher field trial.

chrome/browser/chrome_browser_field_trials.h

Index: chrome/browser/chrome_browser_field_trials.h
diff --git a/chrome/browser/chrome_browser_field_trials.h b/chrome/browser/chrome_browser_field_trials.h
index 3d16f6a188a824875835225373b0a9b10ed3968d..be0b29f68c91856b3480306f52485063fef98d86 100644
--- a/chrome/browser/chrome_browser_field_trials.h
+++ b/chrome/browser/chrome_browser_field_trials.h
@@ -55,6 +55,10 @@ class ChromeBrowserFieldTrials {
   // Sets up field trials for doing Cache Sensitivity Analysis.
   void SetUpCacheSensitivityAnalysisFieldTrial();
 
+  // Disables the show profile switcher field trial if multi-profiles is not
+  // enabled.
+  void DisableShowProfileSwitcherTrialIfNecessary();
+
   // A field trial to determine the impact of using non-blocking reads for
   // TCP sockets on Windows instead of overlapped I/O.
   void WindowsOverlappedTCPReadsFieldTrial();