Adding show profile switcher field trial.

chrome/browser/profiles/avatar_menu_model.cc

Index: chrome/browser/profiles/avatar_menu_model.cc
diff --git a/chrome/browser/profiles/avatar_menu_model.cc b/chrome/browser/profiles/avatar_menu_model.cc
index d6e1418eb59ef0edc0e854e984d736039d6b6b53..6176834a227080bc3668ded25dc090f0bc8cbd72 100644
--- a/chrome/browser/profiles/avatar_menu_model.cc
+++ b/chrome/browser/profiles/avatar_menu_model.cc
@@ -5,6 +5,7 @@
 #include "chrome/browser/profiles/avatar_menu_model.h"
 
 #include "base/bind.h"
+#include "base/metrics/field_trial.h"
 #include "base/stl_util.h"
 #include "base/string_number_conversions.h"
 #include "base/utf_string_conversions.h"
@@ -48,6 +49,10 @@ void OnProfileCreated(bool always_create,
   }
 }
 
+// Constants for the show profile switcher experiment
+const char kShowProfileSwitcherFieldTrialName[] = "ShowProfileSwitcher";
+const char kAlwaysShowSwitcherGroupName[] = "AlwaysShow";
+
 }  // namespace
 
 AvatarMenuModel::AvatarMenuModel(ProfileInfoInterface* profile_cache,
@@ -167,6 +172,12 @@ void AvatarMenuModel::Observe(int type,
 
 // static
 bool AvatarMenuModel::ShouldShowAvatarMenu() {
+  if (base::FieldTrialList::FindFullName(kShowProfileSwitcherFieldTrialName) ==
+      kAlwaysShowSwitcherGroupName) {
+    // We should only be in this group when multi-profiles is enabled.
+    DCHECK(ProfileManager::IsMultipleProfilesEnabled());
+    return true;
+  }
   return ProfileManager::IsMultipleProfilesEnabled() &&
       g_browser_process->profile_manager()->GetNumberOfProfiles() > 1;
 }