Add memory pressure dispatching callback to MemoryCoordinator

components/memory_coordinator/browser/memory_coordinator.cc

Index: components/memory_coordinator/browser/memory_coordinator.cc
diff --git a/components/memory_coordinator/browser/memory_coordinator.cc b/components/memory_coordinator/browser/memory_coordinator.cc
index 634ebf809054e6098c15a500d690643f0cd4fccf..b4e714ab731798c73d0b27712b3ae1a1442356a6 100644
--- a/components/memory_coordinator/browser/memory_coordinator.cc
+++ b/components/memory_coordinator/browser/memory_coordinator.cc
@@ -4,6 +4,8 @@
 
 #include "components/memory_coordinator/browser/memory_coordinator.h"
 
+#include "base/memory/memory_pressure_listener.h"
+
 namespace memory_coordinator {
 
 // The implementation of MemoryCoordinatorHandle. See memory_coordinator.mojom
@@ -31,9 +33,23 @@ class MemoryCoordinatorHandleImpl : public mojom::MemoryCoordinatorHandle {
   DISALLOW_COPY_AND_ASSIGN(MemoryCoordinatorHandleImpl);
 };
 
-MemoryCoordinator::MemoryCoordinator() {}
+MemoryCoordinator::MemoryCoordinator()
+    : pressure_level_dispatcher_(
+          base::Bind(&MemoryCoordinator::OnMemoryPressure,
+                     base::Unretained(this))) {
+  auto* monitor = base::MemoryPressureMonitor::Get();
+  if (monitor) {
+    monitor->SetDispatchCallback(pressure_level_dispatcher_);
+  }
+}
 
-MemoryCoordinator::~MemoryCoordinator() {}
+MemoryCoordinator::~MemoryCoordinator() {
+  auto* monitor = base::MemoryPressureMonitor::Get();
+  if (monitor) {
+    monitor->SetDispatchCallback(
+        base::Bind(&base::MemoryPressureListener::NotifyMemoryPressure));
+  }
+}
 
 void MemoryCoordinator::CreateHandle(
     int render_process_id,
@@ -53,4 +69,19 @@ void MemoryCoordinator::OnConnectionError(int render_process_id) {
   children_.erase(render_process_id);
 }
 
+void MemoryCoordinator::OnMemoryPressure(
+    base::MemoryPressureMonitor::MemoryPressureLevel level) {
+  // TODO(bashi): The current implementation just translates memory pressure
+  // levels to memory coordinator states. The logic will be replaced with
+  // the priority tracker.
+  if (level == base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE) {
+    clients()->Notify(FROM_HERE, &MemoryCoordinatorClient::OnMemoryStateChange,
+                      mojom::MemoryState::THROTTLED);
+  } else if (level ==
+             base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) {
+    clients()->Notify(FROM_HERE, &MemoryCoordinatorClient::OnMemoryStateChange,
+                      mojom::MemoryState::SUSPENDED);
+  }
+}
+
 }  // namespace memory_coordinator