Various work on out of memory managment.

- Improve how we handle processes that have shown UI, to take care
  of more cases where we want to push them into the background LRU
  list.
- New trim memory level for when an application that has done UI
  is no longer visible to the user.
- Add APIs to get new trim memory callback.
- Add a host of new bind flags to tweak how the system will adjust
  the OOM level of the target process.

Change-Id: I23ba354112f411a9f8773a67426b4dff85fa2439
diff --git a/services/java/com/android/server/am/ActivityStack.java b/services/java/com/android/server/am/ActivityStack.java
index cc58eaf..33b21ab 100644
--- a/services/java/com/android/server/am/ActivityStack.java
+++ b/services/java/com/android/server/am/ActivityStack.java
@@ -560,6 +560,7 @@
             showAskCompatModeDialogLocked(r);
             r.compat = mService.compatibilityInfoForPackageLocked(r.info.applicationInfo);
             app.hasShownUi = true;
+            app.pendingUiClean = true;
             app.thread.scheduleLaunchActivity(new Intent(r.intent), r,
                     System.identityHashCode(r),
                     r.info, r.compat, r.icicle, results, newIntents, !andResume,