Enabling history and paging by default

- Removing associated tuner flags

Change-Id: Ia69bf273489b0079c389e7feb1428071569092d5
diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index ffa6a4d..0d645d0 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -862,7 +862,7 @@
             // When this flag is set, we currently take the fullscreen screenshot of the activity
             // but scaled to half the size.  This gives us a "good-enough" fullscreen thumbnail to
             // use within SystemUI while keeping memory usage low.
-            if (mService.mTakeFullscreenScreenshots) {
+            if (ActivityManagerService.TAKE_FULLSCREEN_SCREENSHOTS) {
                 w = h = -1;
                 scale = 0.5f;
             }