guest_view.js should handle actionQueue items in order.

At present, the implementation of destroyImpl() in guest_view_iframe.js
calls handleCallback() in the *middle* of the function, meaning
remaining items in the action queue may complete before destroyImpl()
finishes updating the state, leading to subsequent commands being
dropped if functions like create/attach encounter the non-updated
state.

This fixes a regression introduced in
https://chromium-review.googlesource.com/c/chromium/src/+/528392. It's
not obvious if it introduced any failures, but the original CL bypassed
browser tests as extensions/renderer/BUILD.gn was missing the relevant
files (restored in
https://chromium-review.googlesource.com/c/chromium/src/+/812109).

Bug: 
Change-Id: I83db799b73174d3e996677333e01192bf5321460
Reviewed-on: https://chromium-review.googlesource.com/812005Reviewed-by: Kevin McNee <mcnee@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522438}

extensions/renderer/resources/guest_view/guest_view.js

@@ -259,7 +259,10 @@ GuestViewImpl.prototype.destroyImpl = function(callback) {
   GuestViewInternal.destroyGuest(
       this.id, $Function.bind(this.handleCallback, this, callback));
 
-  // Reset the state of the destroyed guest;
+  // Reset the state of the destroyed guest; it's ok to do this after shipping
+  // the callback to the GuestViewInternal api, since it runs asynchronously,
+  // and the changes below will happen before the next item from the action
+  // queue is executed.
   this.contentWindow = null;
   this.id = 0;
   this.internalInstanceId = 0;

extensions/renderer/resources/guest_view/guest_view_iframe.js

@@ -127,8 +127,6 @@ GuestViewImpl.prototype.destroyImpl = function(callback) {
     GuestViewInternalNatives.DetachGuest(this.internalInstanceId);
   }
 
-  this.handleCallback(callback);
-
   // Reset the state of the destroyed guest;
   this.contentWindow = null;
   this.id = 0;
@@ -137,4 +135,8 @@ GuestViewImpl.prototype.destroyImpl = function(callback) {
   if (ResizeEvent.hasListener(this.callOnResize)) {
     ResizeEvent.removeListener(this.callOnResize);
   }
+
+  // Handle callback at end to avoid handling items in the action queue out of
+  // order, since the callback is run synchronously here.
+  this.handleCallback(callback);
 };