memory_coordinator: Discard tabs under critical memory condition

content/browser/memory/memory_condition_observer.h

Index: content/browser/memory/memory_condition_observer.h
diff --git a/content/browser/memory/memory_condition_observer.h b/content/browser/memory/memory_condition_observer.h
index e2e9975249bdeed303fc33868d7aa44ceffea4a1..40982ff7152952db7b10ea637940cc41d2ef9339 100644
--- a/content/browser/memory/memory_condition_observer.h
+++ b/content/browser/memory/memory_condition_observer.h
@@ -37,6 +37,7 @@ class CONTENT_EXPORT MemoryConditionObserver {
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplTest, CalculateNextCondition);
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplTest, UpdateCondition);
   FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplTest, ForceSetMemoryCondition);
+  FRIEND_TEST_ALL_PREFIXES(MemoryCoordinatorImplTest, DiscardTabUnderCritical);
 
   // Calculates next memory condition from the amount of free memory using
   // a heuristic.