Always use the observer's index in ObserverList.removeObserver().

BUG=349925

Review URL: https://codereview.chromium.org/179793007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255924 0039d316-1c4b-4281-b951-d872f2087c98

base/android/java/src/org/chromium/base/ObserverList.java

@@ -80,7 +80,7 @@ public class ObserverList<E> implements Iterable<E> {
 
         if (mIterationDepth == 0) {
             // No one is iterating over the list.
-            mObservers.remove(obs);
+            mObservers.remove(index);
         } else {
             mObservers.set(index, null);
         }