ObserverList.removeObserver() should not return true when null is being removed.

base/android/javatests/src/org/chromium/base/ObserverListTest.java

Index: base/android/javatests/src/org/chromium/base/ObserverListTest.java
diff --git a/base/android/javatests/src/org/chromium/base/ObserverListTest.java b/base/android/javatests/src/org/chromium/base/ObserverListTest.java
index cb09c2c60c0707142c610bb73676831cd7fbc07c..f999168c53f7f1ee4edec0460d68055957c2491c 100644
--- a/base/android/javatests/src/org/chromium/base/ObserverListTest.java
+++ b/base/android/javatests/src/org/chromium/base/ObserverListTest.java
@@ -245,5 +245,11 @@ public class ObserverListTest extends InstrumentationTestCase {
         assertFalse(observerList.removeObserver(new Object()));
         assertTrue(observerList.removeObserver(b));
         assertFalse(observerList.removeObserver(null));
+
+        // If we remove an object while iterating, it will be replaced by 'null'.
+        observerList.addObserver(a);
+        Iterator<Object> iterator = observerList.iterator();
+        assertTrue(observerList.removeObserver(a));
+        assertFalse(observerList.removeObserver(null));
     }
 }