Change getAccessToken and getExtensionPrinterAccess to sendWithPromise

chrome/browser/resources/print_preview/cloud_print_interface.js

Index: chrome/browser/resources/print_preview/cloud_print_interface.js
diff --git a/chrome/browser/resources/print_preview/cloud_print_interface.js b/chrome/browser/resources/print_preview/cloud_print_interface.js
index cce11fc68825334b07bcd224c6b48a06639809b9..fef14c42d37558a662f4a21b9f53935f35ac2a0b 100644
--- a/chrome/browser/resources/print_preview/cloud_print_interface.js
+++ b/chrome/browser/resources/print_preview/cloud_print_interface.js
@@ -101,13 +101,13 @@ cr.define('cloudprint', function() {
     this.outstandingCloudSearchRequests_ = [];
 
     /**
-     * Event tracker used to keep track of native layer events.
-     * @type {!EventTracker}
-     * @private
+     * Promise that will be resolved when the access token for
+     * DestinationOrigin.DEVICE is available. Null if there is no request
+     * currently pending.
+     * @private {?Promise}
      */
-    this.tracker_ = new EventTracker();
+    this.accessTokenRequestPromise_ = null;
 
-    this.addEventListeners_();
   }
 
   /**
@@ -163,8 +163,6 @@ cr.define('cloudprint', function() {
   CloudPrintInterface.CLOUD_ORIGINS_ = [
     print_preview.DestinationOrigin.COOKIES,
     print_preview.DestinationOrigin.DEVICE
-    // TODO(vitalybuka): Enable when implemented.
-    // ready print_preview.DestinationOrigin.PROFILE
   ];
 
   CloudPrintInterface.prototype = {
@@ -315,17 +313,6 @@ cr.define('cloudprint', function() {
           this.onPrinterDone_.bind(this, printerId)));
     },
 
-    /**
-     * Adds event listeners to relevant events.
-     * @private
-     */
-    addEventListeners_: function() {
-      this.tracker_.add(
-          this.nativeLayer_.getEventTarget(),
-          print_preview.NativeLayer.EventType.ACCESS_TOKEN_READY,
-          this.onAccessTokenReady_.bind(this));
-    },
-
     /**
      * Builds request to the Google Cloud Print API.
      * @param {string} method HTTP method of the request.
@@ -400,12 +387,16 @@ cr.define('cloudprint', function() {
      * @private
      */
     sendOrQueueRequest_: function(request) {
-      if (request.origin == print_preview.DestinationOrigin.COOKIES) {
+      if (request.origin == print_preview.DestinationOrigin.COOKIES)
         return this.sendRequest_(request);

[dpapad, 2017/06/20 16:09:09]

This method is not declaring any @return. Should this be

if (request.origin == print_preview.DestinationOrigin.COOKIES) {
  this.sendRequest_(request);
  return;
}

[rbpotter, 2017/06/21 03:52:28]

I suspect this was done since sendRequest_ does not return anything,
but agree this is more clear. Done.

-      } else {
-        this.requestQueue_.push(request);
-        this.nativeLayer_.startGetAccessToken(request.origin);
-      }
+
+      this.requestQueue_.push(request);

[dpapad, 2017/06/20 16:09:09]

So, is the requestQueue_ necessary anymore? I think we can remove as follows,
WDYT?

Per my understanding this was used to queue a print request, until the
ACCESS_TOKEN_READY event was fired. Once fired, the list was being searched for
the correct authType (not relevant anymore) and a request was sent to the cloud
print API.

Now that we have the Promise, we don't need to queue, all we need to do is to
wait for the Promise.

sendOrQueueRequest_: function(request) {
  if (request.origin == print_preview.DestinationOrigin.COOKIES) {
    this.sendRequest_(request);
    return;
  }

  if (this.accessTokenRequestPromise_ == null) {
    this.accessTokenRequestPromise_ = 
        this.nativeLayer_.getAccessToken(request.origin);
  }

  this.accessTokenRequestPromise_.then(
      this.onAccessTokenReady_.bind(this, request));
}

onAccessTokenReady_: function (request, accessToken) {
  if (accessToken) {
    ...
  } else {
    ...
  }
  this.accessTokenRequestPromise_ = null;
}

[rbpotter, 2017/06/21 03:52:28]

Done. Queue is not needed anymore, thanks for the suggestion.

+      if (this.accessTokenRequestPromise_ != null)
+        return;
+
+      this.accessTokenRequestPromise_ =
+          this.nativeLayer_.getAccessToken(request.origin).then(
+              this.onAccessTokenReady_.bind(this));
     },
 
     /**
@@ -477,29 +468,26 @@ cr.define('cloudprint', function() {
     },
 
     /**
-     * Called when a native layer receives access token.
-     * @param {Event} event Contains the authentication type and access token.
+     * Called when a native layer receives access token. Assumes that the
+     * destination type for this token is DestinationOrigin.DEVICE.
+     * @param {string} accessToken The access token obtained.
      * @private
      */
-    onAccessTokenReady_: function(event) {
-      // TODO(vitalybuka): remove when other Origins implemented.
-      assert(event.authType == print_preview.DestinationOrigin.DEVICE);
-      this.requestQueue_ = this.requestQueue_.filter(function(request) {
+    onAccessTokenReady_: function(accessToken) {
+      this.requestQueue_ = this.requestQueue_.forEach(function(request) {
         assert(request.origin == print_preview.DestinationOrigin.DEVICE);
-        if (request.origin != event.authType) {
-          return true;
-        }
-        if (event.accessToken) {
+        if (accessToken) {
           request.xhr.setRequestHeader(
-              'Authorization', 'Bearer ' + event.accessToken);
+              'Authorization', 'Bearer ' + accessToken);
           this.sendRequest_(request);
         } else {  // No valid token.
           // Without abort status does not exist.
           request.xhr.abort();
           request.callback(request);
         }
-        return false;
       }, this);
+      this.requestQueue_ = [];
+      this.accessTokenRequestPromise_ = null;
     },
 
     /**