Fix leaky view tags

The implementation of the method View#setTag(int, Object) stored tag
objects as entries in a static WeakHashMap associated with the View as
a key. This was problematic for any tag object that stored a hard
reference back to the View the tag was placed on, as it would cause
the WeakReference key to never be collected and the entry to persist
forever.

This was particularly nasty if an app used a keyed tag to store a
ViewHolder object referencing child views for use in the Adapter
implementaion for an AdapterView, since child views will always have
hard references leading back to the parent.

Change-Id: Ia17840a301ba0e0c928861405388fb2f625dac2c

Author: adamp

core/java/android/view/View.java

@@ -81,7 +81,6 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Locale;
-import java.util.WeakHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 /**
@@ -1497,12 +1496,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
     /**
      * Map used to store views' tags.
      */
-    private static WeakHashMap<View, SparseArray<Object>> sTags;
-
-    /**
-     * Lock used to access sTags.
-     */
-    private static final Object sTagsLock = new Object();
+    private SparseArray<Object> mKeyedTags;
 
     /**
      * The next available accessiiblity id.
@@ -12236,14 +12230,7 @@ public void setTag(final Object tag) {
      * @see #getTag()
      */
     public Object getTag(int key) {
-        SparseArray<Object> tags = null;
-        synchronized (sTagsLock) {
-            if (sTags != null) {
-                tags = sTags.get(this);
-            }
-        }
-
-        if (tags != null) return tags.get(key);
+        if (mKeyedTags != null) return mKeyedTags.get(key);
         return null;
     }
 
@@ -12276,7 +12263,7 @@ public void setTag(int key, final Object tag) {
                     + "resource id.");
         }
 
-        setTagInternal(this, key, tag);
+        setKeyedTag(this, key, tag);
     }
 
     /**
@@ -12291,27 +12278,15 @@ public void setTagInternal(int key, Object tag) {
                     + "resource id.");
         }
 
-        setTagInternal(this, key, tag);
+        setKeyedTag(this, key, tag);
     }
 
-    private static void setTagInternal(View view, int key, Object tag) {
-        SparseArray<Object> tags = null;
-        synchronized (sTagsLock) {
-            if (sTags == null) {
-                sTags = new WeakHashMap<View, SparseArray<Object>>();
-            } else {
-                tags = sTags.get(view);
-            }
-        }
-
-        if (tags == null) {
-            tags = new SparseArray<Object>(2);
-            synchronized (sTagsLock) {
-                sTags.put(view, tags);
-            }
+    private void setKeyedTag(View view, int key, Object tag) {
+        if (mKeyedTags == null) {
+            mKeyedTags = new SparseArray<Object>();
         }
 
-        tags.put(key, tag);
+        mKeyedTags.put(key, tag);
     }
 
     /**