TabManagerDelegate: Better prioritize ARC processes.

components/arc/common/process.mojom

Index: components/arc/common/process.mojom
diff --git a/components/arc/common/process.mojom b/components/arc/common/process.mojom
index 6dd05d68d51922eb9f04399ab6d40eb9988e6e8a..916ccdfcd0b2d57834d17d5023b45af89a96c3de 100644
--- a/components/arc/common/process.mojom
+++ b/components/arc/common/process.mojom
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Next MinVersion: 5
+// Next MinVersion: 6
 
 module arc.mojom;
 
@@ -83,10 +83,19 @@ struct RunningAppProcessInfo {
   uint32 pid;
 
   // Current process state.
+  // TODO(cylee): Deprecate it if nobody uses it.
   ProcessState process_state;
 
   // Package names running in the process.
   [MinVersion=4] array<string>? packages;
+
+  // Current OOM adjustment level of the process, calculated by
+  // Android ActivityManagerService.
+  [MinVersion=5] int32 adj;
+
+  // Last time the process was active. Milliseconds since boot.
+  // The clock is monotonic (comes from Android System.uptimeMillis()).
+  [MinVersion=5] int64 last_activity_time;
 };
 
 interface ProcessInstance {