Introduce Page.Events.Request

This patch introduces the 'request' event which is fired when
page has initiated a request.

The event dispatches an instance of Request class.

References #26.

lib/Page.js

@@ -17,7 +17,7 @@
 let fs = require('fs');
 let EventEmitter = require('events');
 let mime = require('mime');
-let {InterceptedRequest} = require('./Request');
+let {Request, InterceptedRequest} = require('./Request');
 let Navigator = require('./Navigator');
 let Dialog = require('./Dialog');
 let FrameManager = require('./FrameManager');
@@ -70,6 +70,7 @@ class Page extends EventEmitter {
 
     client.on('Network.responseReceived', event => this.emit(Page.Events.ResponseReceived, event.response));
     client.on('Network.loadingFailed', event => this.emit(Page.Events.ResourceLoadingFailed, event));
+    client.on('Network.requestWillBeSent', event => this.emit(Page.Events.Request, new Request(event.request)));
     client.on('Page.loadEventFired', event => this.emit(Page.Events.Load));
 
     client.on('Network.requestIntercepted', event => this._onRequestIntercepted(event));
@@ -628,6 +629,7 @@ Page.Events = {
   ConsoleMessage: 'consolemessage',
   Dialog: 'dialog',
   Error: 'error',
+  Request: 'request',
   ResourceLoadingFailed: 'resourceloadingfailed',
   ResponseReceived: 'responsereceived',
   FrameAttached: 'frameattached',

test/test.js

@@ -269,6 +269,16 @@ describe('Puppeteer', function() {
     });
   });
 
+  describe('Page.Events.Request', function() {
+    it('should fire', SX(async function(done) {
+      let requests = [];
+      page.on('request', request => requests.push(request));
+      await page.navigate(EMPTY_PAGE);
+      expect(requests.length).toBe(1);
+      expect(requests[0].url).toContain('empty.html');
+    }));
+  });
+
   describe('Page.screenshot', function() {
     it('should work', SX(async function() {
       await page.setViewportSize({width: 500, height: 500});