Fix null annotations, and move checks into RequestFinishedInfo

components/cronet/android/java/src/org/chromium/net/impl/UrlRequestBuilderImpl.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.impl;
 
 import android.annotation.SuppressLint;
 import android.util.Log;
 import android.util.Pair;
 
 import org.chromium.net.CronetEngine;
 import org.chromium.net.ExperimentalUrlRequest;
 import org.chromium.net.UploadDataProvider;
 import org.chromium.net.UrlRequest;
 
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.concurrent.Executor;
 
 /**
  * Implements {@link org.chromium.net.ExperimentalUrlRequest.Builder}.
  */
 public class UrlRequestBuilderImpl extends ExperimentalUrlRequest.Builder {
     private static final String ACCEPT_ENCODING = "Accept-Encoding";
     private static final String TAG = "UrlRequestBuilder";
 
     // All fields are temporary storage of ExperimentalUrlRequest configuration to be
@@ skipping 13 matching lines @@
     // List of request headers, stored as header field name and value pairs.
     private final ArrayList<Pair<String, String>> mRequestHeaders = new ArrayList<>();
     // Disable the cache for just this request.
     private boolean mDisableCache;
     // Disable connection migration for just this request.
     private boolean mDisableConnectionMigration;
     // Priority of request. Default is medium.
     @CronetEngineBase.RequestPriority
     private int mPriority = REQUEST_PRIORITY_MEDIUM;
     // Request reporting annotations. Avoid extra object creation if no annotations added.
-    private Collection<Object> mRequestAnnotations = Collections.emptyList();
+    private Collection<Object> mRequestAnnotations;
     // If request is an upload, this provides the request body data.
     private UploadDataProvider mUploadDataProvider;
     // Executor to call upload data provider back on.
     private Executor mUploadDataProviderExecutor;
     private boolean mAllowDirectExecutor = false;
 
     /**
      * Creates a builder for {@link UrlRequest} objects. All callbacks for
      * generated {@link UrlRequest} objects will be invoked on
      * {@code executor}'s thread. {@code executor} must not run tasks on the
@@ skipping 93 matching lines @@
     public UrlRequestBuilderImpl allowDirectExecutor() {
         mAllowDirectExecutor = true;
         return this;
     }
 
     @Override
     public UrlRequestBuilderImpl addRequestAnnotation(Object annotation) {
         if (annotation == null) {
             throw new NullPointerException("Invalid metrics annotation.");
         }
-        if (mRequestAnnotations.isEmpty()) {
+        if (mRequestAnnotations == null) {
             mRequestAnnotations = new ArrayList<>();
         }
         mRequestAnnotations.add(annotation);
         return this;
     }
 
     @Override
     public UrlRequestBase build() {
         @SuppressLint("WrongConstant") // TODO(jbudorick): Remove this after rolling to the N SDK.
         final UrlRequestBase request = mCronetEngine.createRequest(mUrl, mCallback, mExecutor,
                 mPriority, mRequestAnnotations, mDisableCache, mDisableConnectionMigration,
                 mAllowDirectExecutor);
         if (mMethod != null) {
             request.setHttpMethod(mMethod);
         }
         for (Pair<String, String> header : mRequestHeaders) {
             request.addHeader(header.first, header.second);
         }
         if (mUploadDataProvider != null) {
             request.setUploadDataProvider(mUploadDataProvider, mUploadDataProviderExecutor);
         }
         return request;
     }
 }