Prevent a memory leak in TextLine.

Bug 5740435

The new SpanSet cached objects should be recycled when the TextLine is
recycled to prevent a reference to their span, which may lead to the
entire activity.

Change-Id: I4469e418a228bd71eb8be1d43ed86de49baba165

Author: Gilles Debunne

core/java/android/text/TextLine.java

@@ -102,6 +102,11 @@ static TextLine recycle(TextLine tl) {
         tl.mText = null;
         tl.mPaint = null;
         tl.mDirections = null;
+
+        tl.mMetricAffectingSpanSpanSet.recycle();
+        tl.mCharacterStyleSpanSet.recycle();
+        tl.mReplacementSpanSpanSet.recycle();
+
         synchronized(sCached) {
             for (int i = 0; i < sCached.length; ++i) {
                 if (sCached[i] == null) {
@@ -919,6 +924,12 @@ int getNextTransition(int start, int limit) {
             }
             return limit;
         }
+
+        public void recycle() {
+            for (int i = 0; i < numberOfSpans; i++) {
+                spans[i] = null; // prevent a leak: no reference kept when TextLine is recycled
+            }
+        }
     }
 
     /**