Add debug to help with b6829431.

Change-Id: Id65f5c7c187072f5a5c1418c83e06c4a6767c658

Author: Craig Mautner

core/java/android/app/FragmentManager.java

@@ -22,6 +22,8 @@
 import android.content.res.Configuration;
 import android.content.res.TypedArray;
 import android.os.Bundle;
+// TODO(cmautner): remove after fixing 6829431.
+import android.os.Debug;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Parcel;
@@ -383,7 +385,8 @@ public FragmentManagerState[] newArray(int size) {
  * Container for fragments associated with an activity.
  */
 final class FragmentManagerImpl extends FragmentManager {
-    static boolean DEBUG = false;
+    // TODO(cmautner): restore to false after fixing 6829431.
+    static boolean DEBUG = true;
     static final String TAG = "FragmentManager";
 
     static final String TARGET_REQUEST_CODE_STATE_TAG = "android:target_req_state";
@@ -732,6 +735,10 @@ public void performPendingDeferredStart(Fragment f) {
 
     void moveToState(Fragment f, int newState, int transit, int transitionStyle,
             boolean keepActive) {
+        // TODO(cmautner): remove after fixing 6829431.
+        if (DEBUG) Log.v(TAG, "moveToState: " + f
+            + " oldState=" + f.mState + " newState=" + newState
+            + " mRemoving=" + f.mRemoving + " Callers=" + Debug.getCallers(5));
         // Fragments that are not currently added will sit in the onCreate() state.
         if (!f.mAdded && newState > Fragment.CREATED) {
             newState = Fragment.CREATED;