Make autoresize follow Chrome's behavior

atom/browser/lib/guest-view-manager.coffee

@@ -56,6 +56,10 @@ createGuest = (embedder, params) ->
       guest.on event, (_, args...) ->
         embedder.send "ATOM_SHELL_GUEST_VIEW_INTERNAL_DISPATCH_EVENT-#{guest.viewInstanceId}", event, args...
 
+  # Autosize.
+  guest.on 'size-changed', (_, args...) ->
+    embedder.send "ATOM_SHELL_GUEST_VIEW_INTERNAL_SIZE_CHANGED", args...
+
   id
 
 # Destroy an existing guest instance.

atom/renderer/lib/guest-view-internal.coffee

@@ -20,13 +20,19 @@ dispatchEvent = (webView, event, args...) ->
   domEvent = new Event(event)
   for f, i in WEB_VIEW_EVENTS[event]
     domEvent[f] = args[i]
-  webView.webviewNode.dispatchEvent domEvent
+  webView.dispatchEvent domEvent
 
 module.exports =
   registerEvents: (webView, viewInstanceId) ->
     ipc.on "ATOM_SHELL_GUEST_VIEW_INTERNAL_DISPATCH_EVENT-#{viewInstanceId}", (event, args...) ->
       dispatchEvent webView, event, args...
 
+    ipc.on 'ATOM_SHELL_GUEST_VIEW_INTERNAL_SIZE_CHANGED', (args...) ->
+      domEvent = new Event('size-changed')
+      for f, i in ['oldWidth', 'oldHeight', 'newWidth', 'newHeight']
+        domEvent[f] = args[i]
+      webView.onSizeChanged domEvent
+
   createGuest: (type, params, callback) ->
     requestId++
     ipc.send 'ATOM_SHELL_GUEST_VIEW_MANAGER_CREATE_GUEST', type, params, requestId

atom/renderer/lib/web-view.coffee

@@ -382,7 +382,7 @@ class WebView
       @attachWindow guestInstanceId, false
     @pendingGuestCreation = true
 
-  @dispatchEvent = (webViewEvent) ->
+  dispatchEvent: (webViewEvent) ->
     @webviewNode.dispatchEvent webViewEvent
 
   # Adds an 'on<event>' property on the webview, which can be used to set/unset