Add new onUidProcAdjChanged callback to be consumed by the camera

service.

The camera service needs to know when individual process oom adj scores
are changed in order to address bug #124224342. When two separate
processes are displayed in split screen and focus is switched between
them, both proc states will remain the same while their oom scores
change. This is a problem if both have access to the camera - we want
only one owner of the camera stream at any given time and for the app
in focus to be the one to own it.

This patch adds a new IUidObserver registration level for individual
process oom score changes. In addition a new callback has been added to
IUidObserver to track these changes.

Change-Id: I68d964f474d20f819f54b614a4e314ce00aac8fb
Bug: 124224342
Test: -- ActivityManagerServiceTest
      -- ActivityManagerProcessStateTest
      -- ActivityManagerFgsBgStartTest
      -- UidObserverControllerTest
      -- NetworkPolicyManagerServiceTest
      -- ShortcutManagerTest2
      -- HintManagerServiceTest
      -- VibrationSettingsTest
      -- CameraEvictionTest#testCamera2AccessCallbackInSplitMode (x100)

native/android/activity_manager.cpp

@@ -45,6 +45,7 @@ struct UidObserver : public BnUidObserver, public virtual IBinder::DeathRecipien
     void onUidIdle(uid_t uid, bool disabled) override;
     void onUidStateChanged(uid_t uid, int32_t procState, int64_t procStateSeq,
                            int32_t capability) override;
+    void onUidProcAdjChanged(uid_t uid) override;
 
     // IBinder::DeathRecipient implementation
     void binderDied(const wp<IBinder>& who) override;
@@ -120,6 +121,8 @@ void UidObserver::onUidActive(uid_t uid __unused) {}
 
 void UidObserver::onUidIdle(uid_t uid __unused, bool disabled __unused) {}
 
+void UidObserver::onUidProcAdjChanged(uid_t uid __unused) {}
+
 void UidObserver::onUidStateChanged(uid_t uid, int32_t procState,
                                     int64_t procStateSeq __unused,
                                     int32_t capability __unused) {