[TabManager] Fix discard only once regression.

chrome/browser/memory/tab_manager.cc

Index: chrome/browser/memory/tab_manager.cc
diff --git a/chrome/browser/memory/tab_manager.cc b/chrome/browser/memory/tab_manager.cc
index f89f8e485d3ec9b492c5bac5f113e00e77bf5392..eef6d4d0351e243cab575989a2875caf4a4bf729 100644
--- a/chrome/browser/memory/tab_manager.cc
+++ b/chrome/browser/memory/tab_manager.cc
@@ -170,9 +170,9 @@ void TabManager::Start() {
   std::string allow_multiple_discards = variations::GetVariationParamValue(
       features::kAutomaticTabDiscarding.name, "AllowMultipleDiscards");
   if (allow_multiple_discards == "true")
-    discard_once_ = true;
-  else
     discard_once_ = false;
+  else
+    discard_once_ = true;
 
   // Check the variation parameter to see if a tab is to be protected for an
   // amount of time after being backgrounded. The value is in seconds.