[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 8e7a88a3256c21ff1b1424c28c75dfe2159ee697..df54610448de626ddb40111d9a36cf60acb03818 100644
--- a/chrome/browser/memory/tab_manager.cc
+++ b/chrome/browser/memory/tab_manager.cc
@@ -167,9 +167,9 @@ 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.