Expose the ability to set an `beforeRequest` function on the xhr object in order…

… to modify the options used to create the request object
* Make Xhr a factory function that returns a unique instance of the xhr function and expose an instance of it on each player's xhr object
* Keep the returned function is backward compatible with the previous xhr
* Add a `beforeRequest` function to the XHR that allows you to override options before the request
* The `beforeRequest` function can be specified on the global `videojs.Hls.xhr` function and it'll be used for all players unless overridden on a per-player level

@@ -6,7 +6,6 @@
  *
  */
 import resolveUrl from './resolve-url';
-import XhrModule from './xhr';
 import {mergeOptions} from 'video.js';
 import Stream from './stream';
 import m3u8 from './m3u8';
@@ -86,7 +85,7 @@ const updateSegments = function(original, update, offset) {
 };
 
 export default class PlaylistLoader extends Stream {
-  constructor(srcUrl, withCredentials) {
+  constructor(srcUrl, hls, withCredentials) {
     super();
     let loader = this;
     let dispose;
@@ -95,6 +94,8 @@ export default class PlaylistLoader extends Stream {
     let playlistRequestError;
     let haveMetadata;
 
+    this.hls_ = hls;
+
     // a flag that disables "expired time"-tracking this setting has
     // no effect when not playing a live stream
     this.trackExpiredTime_ = false;
@@ -261,7 +262,7 @@ export default class PlaylistLoader extends Stream {
       }
 
       // request the new playlist
-      request = XhrModule({
+      request = this.hls_.xhr({
         uri: resolveUrl(loader.master.uri, playlist.uri),
         withCredentials
       }, function(error, request) {
@@ -298,7 +299,7 @@ export default class PlaylistLoader extends Stream {
       }
 
       loader.state = 'HAVE_CURRENT_METADATA';
-      request = XhrModule({
+      request = this.hls_.xhr({
         uri: resolveUrl(loader.master.uri, loader.media().uri),
         withCredentials
       }, function(error, request) {
@@ -310,7 +311,7 @@ export default class PlaylistLoader extends Stream {
     });
 
     // request the specified URL
-    request = XhrModule({
+    request = this.hls_.xhr({
       uri: srcUrl,
       withCredentials
     }, function(error, req) {

@@ -5,7 +5,7 @@
  */
 import PlaylistLoader from './playlist-loader';
 import Playlist from './playlist';
-import xhr from './xhr';
+import xhrFactory from './xhr';
 import {Decrypter, AsyncStream, decrypt} from './decrypter';
 import utils from './bin-utils';
 import {MediaSource, URL} from 'videojs-contrib-media-sources';
@@ -20,7 +20,7 @@ const Hls = {
   AsyncStream,
   decrypt,
   utils,
-  xhr
+  xhr: xhrFactory()
 };
 
 // the desired length of video to maintain in the buffer, in seconds
@@ -416,6 +416,7 @@ export default class HlsHandler extends Component {
       this.options_.withCredentials = videojs.options.hls.withCredentials;
     }
     this.playlists = new Hls.PlaylistLoader(this.source_.src,
+                                            this.tech_.hls,
                                             this.options_.withCredentials);
 
     this.tech_.one('canplay', this.setupFirstPlay.bind(this));
@@ -1224,7 +1225,7 @@ export default class HlsHandler extends Component {
     }
 
     // request the next segment
-    this.segmentXhr_ = Hls.xhr({
+    this.segmentXhr_ = this.tech_.hls.xhr({
       uri: segmentInfo.uri,
       responseType: 'arraybuffer',
       withCredentials: this.source_.withCredentials,
@@ -1504,7 +1505,7 @@ export default class HlsHandler extends Component {
 
     // request the key if the retry limit hasn't been reached
     if (!key.bytes && !keyFailed(key)) {
-      this.keyXhr_ = Hls.xhr({
+      this.keyXhr_ = this.tech_.hls.xhr({
         uri: this.playlistUriToUrl(key.uri),
         responseType: 'arraybuffer',
         withCredentials: settings.withCredentials
@@ -1563,6 +1564,14 @@ const HlsSourceHandler = function(mode) {
         source,
         mode
       });
+
+      tech.hls.xhr = xhrFactory();
+      // Use a global `before` function if specified on videojs.Hls.xhr
+      // but still allow for a per-player override
+      if (videojs.Hls.xhr.beforeRequest) {
+        tech.hls.xhr.beforeRequest = videojs.Hls.xhr.beforeRequest;
+      }
+
       tech.hls.src(source.src);
       return tech.hls;
     },

@@ -2,48 +2,64 @@
  * A wrapper for videojs.xhr that tracks bandwidth.
  */
 import {xhr as videojsXHR, mergeOptions} from 'video.js';
-const xhr = function(options, callback) {
-  // Add a default timeout for all hls requests
-  options = mergeOptions({
-    timeout: 45e3
-  }, options);
-
-  let request = videojsXHR(options, function(error, response) {
-    if (!error && request.response) {
-      request.responseTime = (new Date()).getTime();
-      request.roundTripTime = request.responseTime - request.requestTime;
-      request.bytesReceived = request.response.byteLength || request.response.length;
-      if (!request.bandwidth) {
-        request.bandwidth =
-          Math.floor((request.bytesReceived / request.roundTripTime) * 8 * 1000);
+
+const xhrFactory = function() {
+  const xhr = function XhrFunction(options, callback) {
+    // Add a default timeout for all hls requests
+    options = mergeOptions({
+      timeout: 45e3
+    }, options);
+
+    // Allow an optional user-specified function to modify the option
+    // object before we construct the xhr request
+    if (XhrFunction.beforeRequest &&
+        typeof XhrFunction.beforeRequest === 'function') {
+      let newOptions = XhrFunction.beforeRequest(options);
+
+      if (newOptions) {
+        options = newOptions;
       }
     }
 
-    // videojs.xhr now uses a specific code
-    // on the error object to signal that a request has
-    // timed out errors of setting a boolean on the request object
-    if (error || request.timedout) {
-      request.timedout = request.timedout || (error.code === 'ETIMEDOUT');
-    } else {
-      request.timedout = false;
-    }
+    let request = videojsXHR(options, function(error, response) {
+      if (!error && request.response) {
+        request.responseTime = (new Date()).getTime();
+        request.roundTripTime = request.responseTime - request.requestTime;
+        request.bytesReceived = request.response.byteLength || request.response.length;
+        if (!request.bandwidth) {
+          request.bandwidth =
+            Math.floor((request.bytesReceived / request.roundTripTime) * 8 * 1000);
+        }
+      }
 
-    // videojs.xhr no longer considers status codes outside of 200 and 0
-    // (for file uris) to be errors, but the old XHR did, so emulate that
-    // behavior. Status 206 may be used in response to byterange requests.
-    if (!error &&
-        response.statusCode !== 200 &&
-        response.statusCode !== 206 &&
-        response.statusCode !== 0) {
-      error = new Error('XHR Failed with a response of: ' +
-                        (request && (request.response || request.responseText)));
-    }
+      // videojs.xhr now uses a specific code
+      // on the error object to signal that a request has
+      // timed out errors of setting a boolean on the request object
+      if (error || request.timedout) {
+        request.timedout = request.timedout || (error.code === 'ETIMEDOUT');
+      } else {
+        request.timedout = false;
+      }
+
+      // videojs.xhr no longer considers status codes outside of 200 and 0
+      // (for file uris) to be errors, but the old XHR did, so emulate that
+      // behavior. Status 206 may be used in response to byterange requests.
+      if (!error &&
+          response.statusCode !== 200 &&
+          response.statusCode !== 206 &&
+          response.statusCode !== 0) {
+        error = new Error('XHR Failed with a response of: ' +
+                          (request && (request.response || request.responseText)));
+      }
+
+      callback(error, request);
+    });
 
-    callback(error, request);
-  });
+    request.requestTime = (new Date()).getTime();
+    return request;
+  };
 
-  request.requestTime = (new Date()).getTime();
-  return request;
+  return xhr;
 };
 
-export default xhr;
+export default xhrFactory;

@@ -3363,6 +3363,79 @@ QUnit.test('selectPlaylist does not fail if getComputedStyle returns null', func
   window.getComputedStyle = oldGetComputedStyle;
 });
 
+QUnit.test('Allows specifying the beforeRequest functionon the player', function() {
+  let beforeRequestCalled = false;
+
+  this.player.ready(function() {
+    this.hls.xhr.beforeRequest = function() {
+      beforeRequestCalled = true;
+    };
+  });
+  this.player.src({
+    src: 'master.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+
+  openMediaSource(this.player, this.clock);
+  // master
+  standardXHRResponse(this.requests.shift());
+  // media
+  standardXHRResponse(this.requests.shift());
+
+  QUnit.ok(beforeRequestCalled, 'beforeRequest was called');
+});
+
+QUnit.test('Allows specifying the beforeRequest function globally', function() {
+  let beforeRequestCalled = false;
+
+  videojs.Hls.xhr.beforeRequest = function() {
+    beforeRequestCalled = true;
+  };
+
+  this.player.src({
+    src: 'master.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+
+  QUnit.ok(beforeRequestCalled, 'beforeRequest was called');
+
+  delete videojs.Hls.xhr.beforeRequest;
+});
+
+QUnit.test('Allows overriding the global beforeRequest function', function() {
+  let beforeGlobalRequestCalled = 0;
+  let beforeLocalRequestCalled = 0;
+
+  videojs.Hls.xhr.beforeRequest = function() {
+    beforeGlobalRequestCalled++;
+  };
+
+  this.player.src({
+    src: 'master.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  this.player.ready(function() {
+    this.hls.xhr.beforeRequest = function() {
+      beforeLocalRequestCalled++;
+    };
+  });
+
+  openMediaSource(this.player, this.clock);
+  // master
+  standardXHRResponse(this.requests.shift());
+  // media
+  standardXHRResponse(this.requests.shift());
+  // ts
+  standardXHRResponse(this.requests.shift());
+
+  QUnit.equal(beforeLocalRequestCalled, 2, 'local beforeRequest was called twice ' +
+                                           'for the media playlist and media');
+  QUnit.equal(beforeGlobalRequestCalled, 1, 'global beforeRequest was called once ' +
+                                            'for the master playlist');
+
+  delete videojs.Hls.xhr.beforeRequest;
+});
+
 QUnit.module('Buffer Inspection');
 QUnit.test('detects time range end-point changed by updates', function() {
   let edge;