Add some new experiment constants for activity and power manager.

Activity manager now has constants, starting with two: bg check
and process limit.

Power manager now has constants, starting with one: controlling
disabling of wake locks from cached processes.

Test: manual

Change-Id: I05db42e2104e9d31584f85251412df2d5efb34b6
diff --git a/services/core/java/com/android/server/AlarmManagerService.java b/services/core/java/com/android/server/AlarmManagerService.java
index 0e07ec0..b1560e6 100644
--- a/services/core/java/com/android/server/AlarmManagerService.java
+++ b/services/core/java/com/android/server/AlarmManagerService.java
@@ -275,7 +275,7 @@
                 } catch (IllegalArgumentException e) {
                     // Failed to parse the settings string, log this and move on
                     // with defaults.
-                    Slog.e(TAG, "Bad device idle settings", e);
+                    Slog.e(TAG, "Bad alarm manager settings", e);
                 }
 
                 MIN_FUTURITY = mParser.getLong(KEY_MIN_FUTURITY, DEFAULT_MIN_FUTURITY);