feat(Page): introduce Page.setBypassCSP (#2324)

This patch introduces `page.setBypassCSP` method that allows clients
to ignore Content-Security-Policy for a given page.

Fixes #1229.

docs/api.md

@@ -90,6 +90,7 @@
   * [page.reload(options)](#pagereloadoptions)
   * [page.screenshot([options])](#pagescreenshotoptions)
   * [page.select(selector, ...values)](#pageselectselector-values)
+  * [page.setBypassCSP(enabled)](#pagesetbypasscspenabled)
   * [page.setCacheEnabled(enabled)](#pagesetcacheenabledenabled)
   * [page.setContent(html)](#pagesetcontenthtml)
   * [page.setCookie(...cookies)](#pagesetcookiecookies)
@@ -1176,6 +1177,15 @@ page.select('select#colors', 'red', 'green', 'blue'); // multiple selections
 
 Shortcut for [page.mainFrame().select()](#frameselectselector-values)
 
+#### page.setBypassCSP(enabled)
+- `enabled` <[boolean]> sets bypassing of page's Content-Security-Policy.
+- returns: <[Promise]>
+
+Toggles bypassing page's Content-Security-Policy.
+
+> **NOTE** CSP bypassing happens at the moment of CSP initialization rather then evaluation. Usually this means
+that `page.setBypassCSP` should be called before navigating to the domain.
+
 #### page.setCacheEnabled(enabled)
 - `enabled` <[boolean]> sets the `enabled` state of the cache.
 - returns: <[Promise]>

lib/Page.js

@@ -610,6 +610,13 @@ class Page extends EventEmitter {
     await this._client.send('Emulation.setScriptExecutionDisabled', { value: !enabled });
   }
 
+  /**
+   * @param {boolean} enabled
+   */
+  async setBypassCSP(enabled) {
+    await this._client.send('Page.setBypassCSP', { enabled });
+  }
+
   /**
    * @param {?string} mediaType
    */

test/page.spec.js

@@ -1267,6 +1267,46 @@ module.exports.addTests = function({testRunner, expect, defaultBrowserOptions, p
       });
     });
 
+    describe('Page.setBypassCSP', function() {
+      it('should bypass CSP meta tag', async({page, server}) => {
+        // Make sure CSP prohibits addScriptTag.
+        await page.goto(server.PREFIX + '/csp.html');
+        await page.addScriptTag({content: 'window.__injected = 42;'}).catch(e => void e);
+        expect(await page.evaluate(() => window.__injected)).toBe(undefined);
+
+        // By-pass CSP and try one more time.
+        await page.setBypassCSP(true);
+        await page.reload();
+        await page.addScriptTag({content: 'window.__injected = 42;'});
+        expect(await page.evaluate(() => window.__injected)).toBe(42);
+      });
+
+      it('should bypass CSP header', async({page, server}) => {
+        // Make sure CSP prohibits addScriptTag.
+        server.setCSP('/empty.html', 'default-src "self"');
+        await page.goto(server.EMPTY_PAGE);
+        await page.addScriptTag({content: 'window.__injected = 42;'}).catch(e => void e);
+        expect(await page.evaluate(() => window.__injected)).toBe(undefined);
+
+        // By-pass CSP and try one more time.
+        await page.setBypassCSP(true);
+        await page.reload();
+        await page.addScriptTag({content: 'window.__injected = 42;'});
+        expect(await page.evaluate(() => window.__injected)).toBe(42);
+      });
+
+      it('should bypass after cross-process navigation', async({page, server}) => {
+        await page.setBypassCSP(true);
+        await page.goto(server.PREFIX + '/csp.html');
+        await page.addScriptTag({content: 'window.__injected = 42;'});
+        expect(await page.evaluate(() => window.__injected)).toBe(42);
+
+        await page.goto(server.CROSS_PROCESS_PREFIX + '/csp.html');
+        await page.addScriptTag({content: 'window.__injected = 42;'});
+        expect(await page.evaluate(() => window.__injected)).toBe(42);
+      });
+    });
+
     describe('Page.addScriptTag', function() {
       it('should throw an error if no options are provided', async({page, server}) => {
         let error = null;