arc: Implement proper Arc window activation for task moving to front.

components/arc/common/app.mojom

Index: components/arc/common/app.mojom
diff --git a/components/arc/common/app.mojom b/components/arc/common/app.mojom
index 1110e41be5e13f19a61d2622d38834cb6105214f..7e075dbfdb32311b4153dca27c70986088bf88d1 100644
--- a/components/arc/common/app.mojom
+++ b/components/arc/common/app.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: 13
+// Next MinVersion: 14
 
 module arc.mojom;
 
@@ -56,7 +56,7 @@ enum ShowPackageInfoPage {
   MANAGE_LINKS = 1,
 };
 
-// Next method ID: 13
+// Next method ID: 14
 interface AppHost {
   // Sends newly added ARC app to Chrome. This message is sent when ARC receives
   // package added notification. Multiple apps may be added in the one package.
@@ -100,6 +100,9 @@ interface AppHost {
   // Notifies that task has been activated.
   [MinVersion=4] OnTaskSetActive@6(int32 task_id);
 
+  // Notifies that task has been moved to front.
+  [MinVersion=13] OnTaskMovedToFront@13(int32 task_id);

[reveman, 2016/07/28 14:55:00]

I think this needs to go through the wayland channel as part of the remote shell
interface. We already have messages there that provides the reverse; tell
android to move a task to front as a result of chrome and the user activating a
window. Having two different channels for these type of messages make it
difficult to handle them in the correct order.

Using the wayland interface also makes it easy to add a serial number to the
request that can be used in the future for focus stealing prevention.

[khmel, 2016/07/28 15:13:27]

Ok, will try to use wayland service for this task.

+
   // Notifies that notifications enabled settings in Android is changed.
   [MinVersion=7] OnNotificationsEnabledChanged@7(string package_name,
                                                  bool enabled);