Lower SMS background importance

The messaging app is currently bound with the BIND_NOT_VISIBLE flag
by the system. This keeps it in the oom score 200 slot, which
competes with higher priority processes like foreground services.
Binding with BIND_ALMOST_PERCEPTIBLE will lower its background
importance to 201, keeping it warm in memory for snappier UX but
allows them to die in favor of process doing more important work.

Flag: com.android.server.am.lower_sms_oom_importance
Fixes: 372511805
Test: manual (`adb shell dumpsys activity lru`, background sms
process should have `prcp+1` oom score.)

Change-Id: Ia4fef6afa57ff822e5122e1716ea05462dd1ed48

2 files changed, 21 insertions, 3 deletions

diff --git a/services/core/java/com/android/server/am/flags.aconfig b/services/core/java/com/android/server/am/flags.aconfig
index e89889e794ba..15beeda591d8 100644
--- a/services/core/java/com/android/server/am/flags.aconfig
+++ b/services/core/java/com/android/server/am/flags.aconfig
@@ -319,3 +319,14 @@ flag {
         purpose: PURPOSE_BUGFIX
     }
 }
+
+flag {
+    name: "lower_sms_oom_importance"
+    namespace: "backstage_power"
+    description: "Lower messaging app process oom importance to PERCEPTIBLE_APP_ADJ + 1."
+    bug: "372511805"
+    is_fixed_read_only: true
+    metadata {
+        purpose: PURPOSE_BUGFIX
+    }
+}
diff --git a/services/core/java/com/android/server/appbinding/AppBindingConstants.java b/services/core/java/com/android/server/appbinding/AppBindingConstants.java
index 71847694b1d8..561cc0ef0a3b 100644
--- a/services/core/java/com/android/server/appbinding/AppBindingConstants.java
+++ b/services/core/java/com/android/server/appbinding/AppBindingConstants.java
@@ -102,9 +102,16 @@ public class AppBindingConstants {
 
         boolean smsServiceEnabled = parser.getBoolean(SMS_SERVICE_ENABLED_KEY, true);
 
-        int smsAppBindFlags = parser.getInt(
-                SMS_APP_BIND_FLAGS_KEY,
-                Context.BIND_NOT_VISIBLE | Context.BIND_FOREGROUND_SERVICE);
+        int smsAppBindFlags;
+        if (com.android.server.am.Flags.lowerSmsOomImportance()) {
+            smsAppBindFlags = parser.getInt(
+                    SMS_APP_BIND_FLAGS_KEY,
+                    Context.BIND_ALMOST_PERCEPTIBLE | Context.BIND_FOREGROUND_SERVICE);
+        } else {
+            smsAppBindFlags = parser.getInt(
+                    SMS_APP_BIND_FLAGS_KEY,
+                    Context.BIND_NOT_VISIBLE | Context.BIND_FOREGROUND_SERVICE);
+        }
 
         long serviceStableConnectionThresholdSec = parser.getLong(
                 SERVICE_STABLE_CONNECTION_THRESHOLD_SEC_KEY, TimeUnit.MINUTES.toSeconds(2));