Make HistoryBackend a client of memory coordinator

components/memory_coordinator/common/memory_coordinator_client.h

Index: components/memory_coordinator/common/memory_coordinator_client.h
diff --git a/components/memory_coordinator/common/memory_coordinator_client.h b/components/memory_coordinator/common/memory_coordinator_client.h
index 44a04ad593d3704c1bab9c4e9a1572cac90f4134..269d72f59459f549f15ea21917c50d545ac438b2 100644
--- a/components/memory_coordinator/common/memory_coordinator_client.h
+++ b/components/memory_coordinator/common/memory_coordinator_client.h
@@ -9,6 +9,8 @@
 
 namespace memory_coordinator {
 
+using MemoryState = mojom::MemoryState;
+
 // This is an interface for components which can respond to memory status
 // changes.
 class MemoryCoordinatorClient {
@@ -16,7 +18,7 @@ class MemoryCoordinatorClient {
   virtual ~MemoryCoordinatorClient() {}
 
   // Called when memory state has changed.
-  virtual void OnMemoryStateChange(mojom::MemoryState state) = 0;
+  virtual void OnMemoryStateChange(MemoryState state) = 0;
 };
 
 }  // namespace memory_coordinator