system_api: Add field to disable MediaStore maintenance tasks in ARC.

Use protobuf optional field to support this feature which will be passed
to CrOS (used in ARC) from Chrome.  The service can be scheduled to run
on any API level. See http://b/173906243#comment11 for more details.

BUG=b:173906243
BUG=b:170071013
BUG=b:172010486
BUG=b:153866893
TEST=emerge-${BOARD} system_api

Change-Id: I21d5c6a41c32936fedaa2e98ffc89a0f078fbf44
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2595669
Tested-by: Alan Ding <alanding@chromium.org>
Commit-Queue: Alan Ding <alanding@chromium.org>
Reviewed-by: Yusuke Sato <yusukes@chromium.org>
GitOrigin-RevId: 81c3bc35ca6688fc07cc13583624a1cb17e9c520
diff --git a/dbus/login_manager/arc.proto b/dbus/login_manager/arc.proto
index 4388968..a498d59 100644
--- a/dbus/login_manager/arc.proto
+++ b/dbus/login_manager/arc.proto
@@ -39,8 +39,8 @@
   // Experiment flag for go/arc-file-picker.
   optional bool arc_file_picker_experiment = 3 [default = false];
 
-  // Option to disable ureadahead, emulated ureadahead, and tracing. Used in specialized tests that
-  // generate precise ureadahead packs.
+  // Option to disable ureadahead, emulated ureadahead, and tracing. Used in
+  // specialized tests that generate precise ureadahead packs.
   optional bool disable_ureadahead = 7 [default = false];
 
   // Option to disable by hiding default apps shipped on the system image.
@@ -62,7 +62,11 @@
   optional DalvikMemoryProfile dalvik_memory_profile = 9
       [default = MEMORY_PROFILE_DEFAULT];
 
-  // Next ID to use: 10
+  // Option to disable media store maintenance task scheduling. Used in tests
+  // to prevent unreliable performance measurements and CPU not idle failures.
+  optional bool disable_media_store_maintenance = 10 [default = false];
+
+  // Next ID to use: 11
 }
 
 // ARC upgrade options sent from Chrome to session manager. This message is used