TabManagerDelegate: Better prioritize ARC processes.

components/arc/common/process.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // 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;
 
 // Describes the current process state, as defined by AOSP in
 // android.app.ActivityManager.
 enum ProcessState {
   // Process does not exist.
   NONEXISTENT = -1,
 
   // Process is a persistent system process.
@@ skipping 51 matching lines @@
 
   // Process is being cached for later use and is a client of another cached
   // process that contains activities.
   CACHED_ACTIVITY_CLIENT = 15,
 
   // Process is being cached for later use and is empty.
   CACHED_EMPTY = 16,
 };
 
 // Describes a running ARC process.
 // This struct is a subset of android.app.ActivityManager.RunningAppProcessInfo.

[Luis Héctor Chávez, 2016/06/27 16:18:07]

This is not true anymore.

[cylee1, 2016/06/28 18:14:17]

It's still true since I added the 2 attributes to RunningAppProcessInfo in
another CL (sent for review).

 struct RunningAppProcessInfo {
   // Name of the process.
   string process_name;
 
   // PID (within ARC's PID namespace) of the process.
   uint32 pid;
 
   // Current process state.
+  // TODO(cylee): Deprecate it if nobody uses it.

[Yusuke Sato, 2016/06/27 16:40:51]

I think https://codereview.chromium.org/2059483003 uses the field/enum.

[cylee1, 2016/07/14 19:15:24]

I see. In my first implementation I should change the code there as well.
But in the new implementation process_state is remained.

   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;

[Yusuke Sato, 2016/06/27 16:40:51]

I understand AMS calls this "adj" but in Chromium, can you use a more
descriptive name? Most Chromium developers are not familiar with Android
internals.

https://google.github.io/styleguide/cppguide.html#General_Naming_Rules

[cylee1, 2016/07/14 19:15:24]

Changed.

+
+  // Last time the process is active. Milliseconds since boot.

[Luis Héctor Chávez, 2016/06/27 16:18:07]

nit: "process was active". Also, please mention if this is wall or monotonic
time.

[cylee1, 2016/06/28 18:14:17]

Done.

+  [MinVersion=5] int64 last_activity_time;
 };
 
 interface ProcessInstance {
   // Requests ARC instance to return the current process list.
   RequestProcessList@0() => (array<RunningAppProcessInfo> processes);
 
   // Requests ARC instance to kill a process.
   [MinVersion=1]
   KillProcess@1(uint32 pid, string reason);
 
   // Sets oom_score_adj of a process.
   [MinVersion=2]
   SetOomScoreAdj@2(uint32 pid, int32 score);
 
   // Disables Android built-in oom_adj adjustment.
   [MinVersion=2]
   DisableBuiltinOomAdjustment@3();
 
   // Disables Android lowmemorykiller.
   [MinVersion=3]
   DisableLowMemoryKiller@4();
 };