Give transitioning fragment a context prior to retrieving transition

Bug 23688972

An incoming fragment that is going to execute a transition may
need to have a context in order to load the transition. This
CL moves the state of incoming fragments to CREATED prior to
getting their Transitions.

Change-Id: I08b8cda479f7542fb326aa4f0f62a07ccc5662b0

core/java/android/app/BackStackRecord.java

@@ -957,6 +957,7 @@ final class BackStackRecord extends FragmentTransaction implements
      */
     private TransitionState beginTransition(SparseArray<Fragment> firstOutFragments,
             SparseArray<Fragment> lastInFragments, boolean isBack) {
+        ensureFragmentsAreInitialized(lastInFragments);
         TransitionState state = new TransitionState();
 
         // Adding a non-existent target view makes sure that the transitions don't target
@@ -982,6 +983,20 @@ final class BackStackRecord extends FragmentTransaction implements
         return state;
     }
 
+    /**
+     * Ensure that fragments that are entering are at least at the CREATED state
+     * so that they may load Transitions using TransitionInflater.
+     */
+    private void ensureFragmentsAreInitialized(SparseArray<Fragment> lastInFragments) {
+        final int count = lastInFragments.size();
+        for (int i = 0; i < count; i++) {
+            final Fragment fragment = lastInFragments.valueAt(i);
+            if (fragment.mState < Fragment.CREATED) {
+                mManager.moveToState(fragment, Fragment.CREATED, 0, 0, false);
+            }
+        }
+    }
+
     private static Transition cloneTransition(Transition transition) {
         if (transition != null) {
             transition = transition.clone();