Perform printer setup on Chrome OS before selecting printer.

chrome/browser/resources/print_preview/search/cros_destination_resolver.js

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+cr.define('print_preview', function() {
+  'use strict';
+
+  /** @enum {string} */
+  var ResolverState = {
+    INITIAL: 'INITIAL',
+    CONFIGURING_PRINTER: 'CONFIGURING_PRINTER',
+    ERROR: 'ERROR',
+    DONE: 'DONE'
+  };
+
+  /**
+   * Overlay used to notify the user of printer setup steps for Chrome OS
+   * printers.  Printer installation can occur before any print job is executed.
+   *
+   * @param {!print_preview.DestinationStore} destinationStore The destination
+   *    store containing the destination. Used as a proxy to native layer for
+   *    resolving the destination.
+   * @param {!print_preview.Destination} destination The destination that has
+   *     to be resolved.
+   * @constructor
+   * @extends {print_preview.Overlay}
+   */
+  function CrosDestinationResolver(destinationStore, destination) {
+    print_preview.Overlay.call(this);
+
+    /** @private {!print_preview.DestinationStore} */
+    this.destinationStore_ = destinationStore;
+    /** @private {!print_preview.Destination} */
+    this.destination_ = destination;
+
+    /** @private {ResolverState} */

[dpapad, 2017/01/11 20:36:30]

!ResolverState

[skau, 2017/01/12 00:36:16]

Done.

+    this.state_ = ResolverState.INITIAL;
+
+    /**
+     * Promise resolver for promise returned by {@code this.run}.
+     * @private {?PromiseResolver<!print_preview.Destination>}
+     */
+    this.promiseResolver_ = null;
+  };
+
+  CrosDestinationResolver.prototype = {
+    __proto__: print_preview.Overlay.prototype,
+
+    /** @override */
+    enterDocument: function() {
+      print_preview.Overlay.prototype.enterDocument.call(this);
+
+      this.tracker.add(
+          this.destinationStore_,
+          print_preview.DestinationStore.EventType.PRINTER_CONFIGURED,
+          this.onDestinationResolved_.bind(this));
+

[dpapad, 2017/01/11 20:36:30]

Unnecessary blank line.

[skau, 2017/01/12 00:36:16]

Done.

+    },
+
+    /** @override */
+    createDom: function() {
+      this.setElementInternal(this.cloneTemplateInternal(
+          'cros-printer-resolver'));
+    },
+
+    /**
+     * Dispatch the request to resolve the destination to the native layer.
+     * @private
+     */
+    startResolveDestination_: function() {
+      assert(this.state_ == ResolverState.INITIAL);
+      assert(!this.promiseResolver_, "Promise resolver already set");
+      this.promiseResolver_ = new PromiseResolver();
+      this.destinationStore_.resolveCrosDestination(this.destination_);
+      this.setState_(ResolverState.CONFIGURING_PRINTER);
+    },
+
+    /**
+     * Handler for PRINTER_SETUP event. It finalizes the
+     * resolver state once the destination associated with the resolver gets
+     * resolved.
+     * @param {Event} event
+     * @private
+     */
+    onDestinationResolved_: function(event) {
+      assert(this.promiseResolver_, "Promise resolver collected while waiting");

[dpapad, 2017/01/11 20:36:30]

What do you mean by "collected"? Garbage collected? This seems impossible since
this class is holding a reference to this.promiseResolver_. Probably less
confusing to simply restate to "Promise resolver not found"

[skau, 2017/01/12 00:36:16]

The promise resolver is set to null after it has been fulfilled.  I've updated
the message per your suggestion.

+      if (event.success) {
+        this.setState_(ResolverState.DONE);
+        assert(event.capabilities);
+        // event contains printerId and capabilities.
+        this.promiseResolver_.resolve(event);
+        this.setIsVisible(false);
+      } else {
+        this.setState_(ResolverState.ERROR);
+        this.promiseResolver_.reject();
+      }
+
+      this.promiseResolver_ = null;
+    },
+
+    /**
+     * Sets new resolver state and updates the UI accordingly.
+     * @param {ResolverState} state
+     * @private
+     */
+    setState_: function(state) {
+      if (this.state_ == state)
+        return;
+
+      this.state_ = state;
+      this.updateUI_();
+    },
+
+    /**
+     * Updates the resolver overlay UI to match the resolver state.
+     * @private
+     */
+    updateUI_: function() {
+      // TOOD(crbug.com/677567): Replace with meaningful UI.

[dpapad, 2017/01/11 20:36:30]

s/TOOD/TODO

[skau, 2017/01/12 00:36:16]

Done.

+    },
+
+    /**
+     * Initiates and shows the resolver overlay.
+     * @param {!HTMLElement} parent The element that should parent the resolver
+     *     UI.
+     * @return {!Promise<!print_preview.Destination>} Promise that will be
+     * fulfilled when the destination resolving is finished.

[dpapad, 2017/01/11 20:36:30]

Indentation off

[skau, 2017/01/12 00:36:16]

Is there a linter that would catch this?

[dpapad, 2017/01/12 01:18:10]

Not to my knowledge. And to be fair, this is an ambitious goal (having a well
working linter for JSDoc comments, which are not "standard" by any means). We
are not even at the point where we have a well working linter for JS itself (in
Chromium), but we are making progress on this front.

Having said that, you might want to try running clang-format and see if that
would fix it automatically.

[skau, 2017/01/12 02:17:17]

Good to know.  I just tried clang-format and it definitely ignores JSDoc.

+     */
+    run: function(parent) {
+      this.render(parent);
+      this.setIsVisible(true);
+      this.startResolveDestination_();
+
+      assert(this.promiseResolver_, 'Promise resolver not created.');
+      return this.promiseResolver_.promise;
+    }
+  };
+
+  return {
+    CrosDestinationResolver: CrosDestinationResolver
+  };
+});