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..5e4c231c8178ab3f56800800c8446ca88cf4ef79 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 +83,18 @@ struct RunningAppProcessInfo {
   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 {