Plumb onTrimMemory app callback to virtualizationservice

Virtualizationservice uses this hint to reclaim guest memory
via the virtio balloon.

Bug: 238931615
Test: atest MicrodroidBenchmarks
Change-Id: Ie4e70160a3305dec68def27667cecd4cd543293f
diff --git a/virtualizationservice/src/aidl.rs b/virtualizationservice/src/aidl.rs
index 040c0d8..7d24a32 100644
--- a/virtualizationservice/src/aidl.rs
+++ b/virtualizationservice/src/aidl.rs
@@ -27,6 +27,7 @@
     IVirtualMachine::{BnVirtualMachine, IVirtualMachine},
     IVirtualMachineCallback::IVirtualMachineCallback,
     IVirtualizationService::IVirtualizationService,
+    MemoryTrimLevel::MemoryTrimLevel,
     Partition::Partition,
     PartitionType::PartitionType,
     VirtualMachineAppConfig::{Payload::Payload, VirtualMachineAppConfig},
@@ -961,6 +962,13 @@
         })
     }
 
+    fn onTrimMemory(&self, level: MemoryTrimLevel) -> binder::Result<()> {
+        self.instance.trim_memory(level).map_err(|e| {
+            error!("Error trimming VM with CID {}: {:?}", self.instance.cid, e);
+            Status::new_service_specific_error_str(-1, Some(e.to_string()))
+        })
+    }
+
     fn connectVsock(&self, port: i32) -> binder::Result<ParcelFileDescriptor> {
         if !matches!(&*self.instance.vm_state.lock().unwrap(), VmState::Running { .. }) {
             return Err(Status::new_service_specific_error_str(-1, Some("VM is not running")));