refactor(firefox): introduce /lib/Events (#3949)

Declare all events in `/lib/Events.js`, similarly to how
we do it in Puppeteer.

experimental/puppeteer-firefox/lib/Browser.js

@@ -1,5 +1,6 @@
 const {helper, assert} = require('./helper');
 const {Page} = require('./Page');
+const {Events} = require('./Events');
 const EventEmitter = require('events');
 
 class Browser extends EventEmitter {
@@ -109,14 +110,14 @@ class Browser extends EventEmitter {
       return existingTarget;
     let resolve;
     const targetPromise = new Promise(x => resolve = x);
-    this.on(Browser.Events.TargetCreated, check);
+    this.on(Events.Browser.TargetCreated, check);
     this.on('targetchanged', check);
     try {
       if (!timeout)
         return await targetPromise;
       return await helper.waitWithTimeout(targetPromise, 'target', timeout);
     } finally {
-      this.removeListener(Browser.Events.TargetCreated, check);
+      this.removeListener(Events.Browser.TargetCreated, check);
       this.removeListener('targetchanged', check);
     }
 
@@ -161,22 +162,22 @@ class Browser extends EventEmitter {
     const context = browserContextId ? this._contexts.get(browserContextId) : this._defaultContext;
     const target = new Target(this._connection, this, context, pageId, url);
     this._pageTargets.set(pageId, target);
-    this.emit(Browser.Events.TargetCreated, target);
+    this.emit(Events.Browser.TargetCreated, target);
-    context.emit(BrowserContext.Events.TargetCreated, target);
+    context.emit(Events.BrowserContext.TargetCreated, target);
   }
 
   _onTabClosed({pageId}) {
     const target = this._pageTargets.get(pageId);
     this._pageTargets.delete(pageId);
-    this.emit(Browser.Events.TargetDestroyed, target);
+    this.emit(Events.Browser.TargetDestroyed, target);
-    target.browserContext().emit(BrowserContext.Events.TargetDestroyed, target);
+    target.browserContext().emit(Events.BrowserContext.TargetDestroyed, target);
   }
 
   _onTabNavigated({pageId, url}) {
     const target = this._pageTargets.get(pageId);
     target._url = url;
-    this.emit(Browser.Events.TargetChanged, target);
+    this.emit(Events.Browser.TargetChanged, target);
-    target.browserContext().emit(BrowserContext.Events.TargetChanged, target);
+    target.browserContext().emit(Events.BrowserContext.TargetChanged, target);
   }
 
   async close() {
@@ -185,13 +186,6 @@ class Browser extends EventEmitter {
   }
 }
 
-/** @enum {string} */
-Browser.Events = {
-  TargetCreated: 'targetcreated',
-  TargetChanged: 'targetchanged',
-  TargetDestroyed: 'targetdestroyed'
-}
-
 class Target {
   /**
    *
@@ -305,11 +299,4 @@ class BrowserContext extends EventEmitter {
   }
 }
 
-/** @enum {string} */
-BrowserContext.Events = {
-  TargetCreated: 'targetcreated',
-  TargetChanged: 'targetchanged',
-  TargetDestroyed: 'targetdestroyed'
-}
-
 module.exports = {Browser, BrowserContext, Target};

experimental/puppeteer-firefox/lib/Connection.js

@@ -15,6 +15,7 @@
  */
 const debugProtocol = require('debug')('hdfox:protocol');
 const EventEmitter = require('events');
+const {Events} = require('./Events');
 
 /**
  * @internal
@@ -84,7 +85,7 @@ class Connection extends EventEmitter {
     for (const callback of this._callbacks.values())
       callback.reject(rewriteError(callback.error, `Protocol error (${callback.method}): Target closed.`));
     this._callbacks.clear();
-    this.emit(Connection.Events.Disconnected);
+    this.emit(Events.Connection.Disconnected);
   }
 
   dispose() {
@@ -93,10 +94,6 @@ class Connection extends EventEmitter {
   }
 }
 
-Connection.Events = {
-  Disconnected: Symbol('Connection.Events.Disconnected'),
-};
-
 /**
  * @param {!Error} error
  * @param {string} method

experimental/puppeteer-firefox/lib/Events.js

@@ -0,0 +1,29 @@
+const Events = {
+  Page: {
+    Close: 'close',
+    Console: 'console',
+    Dialog: 'dialog',
+    DOMContentLoaded: 'domcontentloaded',
+    FrameAttached: 'frameattached',
+    FrameDetached: 'framedetached',
+    FrameNavigated: 'framenavigated',
+    Load: 'load',
+    PageError: 'pageerror',
+  },
+  Browser: {
+    TargetCreated: 'targetcreated',
+    TargetChanged: 'targetchanged',
+    TargetDestroyed: 'targetdestroyed',
+  },
+  BrowserContext: {
+    TargetCreated: 'targetcreated',
+    TargetChanged: 'targetchanged',
+    TargetDestroyed: 'targetdestroyed',
+  },
+
+  Connection: {
+    Disconnected: Symbol('Events.Connection.Disconnected'),
+  },
+};
+
+module.exports = {Events};

experimental/puppeteer-firefox/lib/Page.js

@@ -8,6 +8,7 @@ const mime = require('mime');
 const util = require('util');
 const EventEmitter = require('events');
 const {JSHandle, createHandle} = require('./JSHandle');
+const {Events} = require('./Events');
 
 const writeFileAsync = util.promisify(fs.writeFile);
 const readFileAsync = util.promisify(fs.readFile);
@@ -90,7 +91,7 @@ class Page extends EventEmitter {
   _onUncaughtError(params) {
     let error = new Error(params.message);
     error.stack = params.stack;
-    this.emit(Page.Events.PageError, error);
+    this.emit(Events.Page.PageError, error);
   }
 
   viewport() {
@@ -154,7 +155,7 @@ class Page extends EventEmitter {
   }
 
   _onDialogOpened(params) {
-    this.emit(Page.Events.Dialog, new Dialog(this._session, params));
+    this.emit(Events.Page.Dialog, new Dialog(this._session, params));
   }
 
   _onFrameAttached(params) {
@@ -168,7 +169,7 @@ class Page extends EventEmitter {
       this._mainFrame = frame;
     }
     this._frames.set(params.frameId, frame);
-    this.emit(Page.Events.FrameAttached, frame);
+    this.emit(Events.Page.FrameAttached, frame);
   }
 
   mainFrame() {
@@ -179,7 +180,7 @@ class Page extends EventEmitter {
     const frame = this._frames.get(params.frameId);
     this._frames.delete(params.frameId);
     frame._detach();
-    this.emit(Page.Events.FrameDetached, frame);
+    this.emit(Events.Page.FrameDetached, frame);
   }
 
   _onNavigationCommitted(params) {
@@ -187,13 +188,13 @@ class Page extends EventEmitter {
     frame._navigated(params.url, params.name, params.navigationId);
     frame._DOMContentLoadedFired = false;
     frame._loadFired = false;
-    this.emit(Page.Events.FrameNavigated, frame);
+    this.emit(Events.Page.FrameNavigated, frame);
   }
 
   _onSameDocumentNavigation(params) {
     const frame = this._frames.get(params.frameId);
     frame._url = params.url;
-    this.emit(Page.Events.FrameNavigated, frame);
+    this.emit(Events.Page.FrameNavigated, frame);
   }
 
   get keyboard(){
@@ -578,7 +579,7 @@ class Page extends EventEmitter {
   _onClosed() {
     this._isClosed = true;
     helper.removeEventListeners(this._eventListeners);
-    this.emit(Page.Events.Close);
+    this.emit(Events.Page.Close);
   }
 
   _onEventFired({frameId, name}) {
@@ -586,9 +587,9 @@ class Page extends EventEmitter {
     frame._firedEvents.add(name.toLowerCase());
     if (frame === this._mainFrame) {
       if (name === 'load')
-        this.emit(Page.Events.Load);
+        this.emit(Events.Page.Load);
       else if (name === 'DOMContentLoaded')
-        this.emit(Page.Events.DOMContentLoaded);
+        this.emit(Events.Page.DOMContentLoaded);
     }
   }
 
@@ -599,7 +600,7 @@ class Page extends EventEmitter {
 
   _onConsole({type, args, frameId}) {
     const frame = this._frames.get(frameId);
-    this.emit(Page.Events.Console, new ConsoleMessage(type, args.map(arg => createHandle(frame, arg))));
+    this.emit(Events.Page.Console, new ConsoleMessage(type, args.map(arg => createHandle(frame, arg))));
   }
 
   /**
@@ -610,19 +611,6 @@ class Page extends EventEmitter {
   }
 }
 
-/** @enum {string} */
-Page.Events = {
-  Close: 'close',
-  Console: 'console',
-  Dialog: 'dialog',
-  DOMContentLoaded: 'domcontentloaded',
-  FrameAttached: 'frameattached',
-  FrameDetached: 'framedetached',
-  FrameNavigated: 'framenavigated',
-  Load: 'load',
-  PageError: 'pageerror'
-}
-
 class ConsoleMessage {
   /**
    * @param {string} type