Add note to ContentViewCore.destroy

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index df0b303d607693f341c0dbb642d36be7a17bf401..4ff6459170511ab7465fd783b9a0f322e96ef42b 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -986,6 +986,10 @@ public class ContentViewCore
      * called after the ContentView has been removed from the view system. No
      * other methods may be called on this ContentView after this method has
      * been called.
+     * Warning: destroy() is not guranteed to be called in Android WebView.
+     * Any object that relies solely on destroy() being called to be cleaned up
+     * will leak in Android WebView. If appropriate, consider clean up in
+     * onDetachedFromWindow() which is guaranteed to be called in Android WebView.
      */
     public void destroy() {
         if (mNativeContentViewCore != 0) {
@@ -1010,6 +1014,8 @@ public class ContentViewCore
         ScreenOrientationListener.getInstance().removeObserver(this);
         mPositionObserver.clearListener();
         mContainerViewObservers.clear();
+
+        // See warning in javadoc before adding more clean up code here.
     }
 
     private void unregisterAccessibilityContentObserver() {