memory coordinator: Add trace macros to track state changes

base/memory/memory_coordinator_client.h

Index: base/memory/memory_coordinator_client.h
diff --git a/base/memory/memory_coordinator_client.h b/base/memory/memory_coordinator_client.h
index d63b17cc1f8b88779dfaa83b7a677529dbc37573..6e75a4d00670ba6d5f47672f7d6ffb6a33ca30d2 100644
--- a/base/memory/memory_coordinator_client.h
+++ b/base/memory/memory_coordinator_client.h
@@ -5,6 +5,8 @@
 #ifndef BASE_MEMORY_MEMORY_COORDINATOR_CLIENT_H_
 #define BASE_MEMORY_MEMORY_COORDINATOR_CLIENT_H_
 
+#include <stdint.h>
+
 #include "base/base_export.h"
 
 namespace base {
@@ -22,7 +24,7 @@ namespace base {
 // MemoryState is an indicator that processes can use to guide their memory
 // allocation policies. For example, a process that receives the suspended
 // state can use that as as signal to drop memory caches.
-enum class MemoryState {
+enum class MemoryState : int32_t {
   // The state is unknown.
   UNKNOWN = -1,
   // No memory constraints.