Implement NetworkManager

This patch implements NetworkManager, which encapsulates all the
interaction with Network domain.

The NetworkManager also uses partial implementation of Request and
Response classes, defined in the Fetch API specification.

References #26

test/test.js

@@ -254,8 +254,8 @@ describe('Puppeteer', function() {
       let success = await page.navigate(EMPTY_PAGE);
       expect(success).toBe(true);
     }));
-    it('should show extraHTTPHeaders', SX(async function() {
-      await page.setExtraHTTPHeaders({
+    it('should show custom HTTP headers', SX(async function() {
+      await page.setHTTPHeaders({
         foo: 'bar'
       });
       page.setRequestInterceptor(request => {
@@ -272,11 +272,11 @@ describe('Puppeteer', function() {
         else
           request.continue();
       });
-      let failedResources = 0;
-      page.on('resourceloadingfailed', event => ++failedResources);
+      let failedRequests = 0;
+      page.on('requestfailed', event => ++failedRequests);
       let success = await page.navigate(STATIC_PREFIX + '/one-style.html');
       expect(success).toBe(true);
-      expect(failedResources).toBe(1);
+      expect(failedRequests).toBe(1);
     }));
     it('should amend HTTP headers', SX(async function() {
       await page.navigate(EMPTY_PAGE);
@@ -478,6 +478,76 @@ describe('Puppeteer', function() {
       expect(await page.evaluate(() => result)).toBe('Clicked');
     }));
   });
+  describe('Page.setUserAgent', function() {
+    it('should work', SX(async function() {
+      expect(page.userAgent()).toContain('Mozilla');
+      page.setUserAgent('foobar');
+      page.navigate(EMPTY_PAGE);
+      let request = await staticServer.waitForRequest('/empty.html');
+      expect(request.headers['user-agent']).toBe('foobar');
+    }));
+  });
+  describe('Page.setHTTPHeaders', function() {
+    it('should work', SX(async function() {
+      expect(page.httpHeaders()).toEqual({});
+      page.setHTTPHeaders({'foo': 'bar'});
+      expect(page.httpHeaders()).toEqual({'foo': 'bar'});
+      page.navigate(EMPTY_PAGE);
+      let request = await staticServer.waitForRequest('/empty.html');
+      expect(request.headers['foo']).toBe('bar');
+    }));
+  });
+  describe('Network Events', function() {
+    it('Page.Events.Request', SX(async function() {
+      let requests = [];
+      page.on('request', request => requests.push(request));
+      await page.navigate(EMPTY_PAGE);
+      expect(requests.length).toBe(1);
+      expect(requests[0].url).toBe(EMPTY_PAGE);
+      expect(requests[0].method).toBe('GET');
+      expect(requests[0].response()).toBeTruthy();
+    }));
+    it('Page.Events.Response', SX(async function() {
+      let responses = [];
+      page.on('response', response => responses.push(response));
+      await page.navigate(EMPTY_PAGE);
+      expect(responses.length).toBe(1);
+      expect(responses[0].url).toBe(EMPTY_PAGE);
+      expect(responses[0].status).toBe(200);
+      expect(responses[0].ok).toBe(true);
+      expect(responses[0].request()).toBeTruthy();
+    }));
+    it('Page.Events.RequestFailed', SX(async function() {
+      page.setRequestInterceptor(request => {
+        if (request.url.endsWith('css'))
+          request.abort();
+        else
+          request.continue();
+      });
+      let failedRequests = [];
+      page.on('requestfailed', request => failedRequests.push(request));
+      await page.navigate(STATIC_PREFIX + '/one-style.html');
+      expect(failedRequests.length).toBe(1);
+      expect(failedRequests[0].url).toContain('one-style.css');
+      expect(failedRequests[0].response()).toBe(null);
+    }));
+    it('Page.Events.RequestFinished', SX(async function() {
+      let requests = [];
+      page.on('requestfinished', request => requests.push(request));
+      await page.navigate(EMPTY_PAGE);
+      expect(requests.length).toBe(1);
+      expect(requests[0].url).toBe(EMPTY_PAGE);
+      expect(requests[0].response()).toBeTruthy();
+    }));
+    it('should fire events in proper order', SX(async function() {
+      let events = [];
+      page.on('request', request => events.push('request'));
+      page.on('response', response => events.push('response'));
+      page.on('requestfinished', request => events.push('requestfinished'));
+      await page.navigate(EMPTY_PAGE);
+      expect(events).toEqual(['request', 'response', 'requestfinished']);
+    }));
+  });
 });
 
 // Since Jasmine doesn't like async functions, they should be wrapped