Fix null annotations, and move checks into RequestFinishedInfo

components/cronet/android/api/src/org/chromium/net/RequestFinishedInfo.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.net;
 
 import android.support.annotation.IntDef;
 import android.support.annotation.Nullable;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Date;
 import java.util.concurrent.Executor;
 
 /**
  * Information about a finished request. Passed to {@link RequestFinishedInfo.Listener}.
  *
  * {@hide} as it's a prototype.
  */
 public final class RequestFinishedInfo {
     /**
@@ skipping 268 matching lines @@
         mException = exception;
     }
 
     /** Returns the request's original URL. */
     public String getUrl() {
         return mUrl;
     }
 
     /** Returns the objects that the caller has supplied when initiating the request. */
     public Collection<Object> getAnnotations() {
+        if (mAnnotations == null) {
+            return Collections.emptyList();
+        }
         return mAnnotations;
     }
 
     // TODO(klm): Collect and return a chain of Metrics objects for redirect responses.
     // TODO(mgersh): Update this javadoc when new metrics are fully implemented
     /**
      * Returns metrics collected for this request.
      *
      * <p>The reported times and bytes account for all redirects, i.e.
      * the TTFB is from the start of the original request to the ultimate response headers,
@@ skipping 30 matching lines @@
      * If the request failed, returns the same {@link UrlRequestException} provided to
      * {@link UrlRequest.Callback#onFailed}.
      *
      * @return the request's {@link UrlRequestException}, if the request failed
      */
     @Nullable
     public UrlRequestException getException() {
         return mException;
     }
 }