memory coordinator: Add trace macros to track state changes

content/child/memory/child_memory_coordinator_impl.cc

Index: content/child/memory/child_memory_coordinator_impl.cc
diff --git a/content/child/memory/child_memory_coordinator_impl.cc b/content/child/memory/child_memory_coordinator_impl.cc
index 5412c6458efa83a116c6b8204f4d98fb74deab56..1e6339926d28f3e94fdc354e65b921cc1ead2047 100644
--- a/content/child/memory/child_memory_coordinator_impl.cc
+++ b/content/child/memory/child_memory_coordinator_impl.cc
@@ -7,6 +7,7 @@
 #include "base/lazy_instance.h"
 #include "base/memory/memory_coordinator_client_registry.h"
 #include "base/synchronization/lock.h"
+#include "base/trace_event/trace_event.h"
 
 namespace content {
 
@@ -58,6 +59,8 @@ ChildMemoryCoordinatorImpl::~ChildMemoryCoordinatorImpl() {
 
 void ChildMemoryCoordinatorImpl::OnStateChange(mojom::MemoryState state) {
   base::MemoryState base_state = ToBaseMemoryState(state);
+  TRACE_EVENT1("memory-infra", "ChildMemoryCoordinatorImpl::OnStateChange",
+               "state", MemoryStateToString(base_state));
   base::MemoryCoordinatorClientRegistry::GetInstance()->Notify(
       base_state);
 }