Native api to get OAuth2 access tokens in Print Preview Web UI.

chrome/browser/resources/print_preview/native_layer.js

Index: chrome/browser/resources/print_preview/native_layer.js
diff --git a/chrome/browser/resources/print_preview/native_layer.js b/chrome/browser/resources/print_preview/native_layer.js
index 988601f49b98f39033809c50a00b81ff8e2135b0..1d2c8635e6128c1a8d8fbb664f056d7fcd9f5630 100644
--- a/chrome/browser/resources/print_preview/native_layer.js
+++ b/chrome/browser/resources/print_preview/native_layer.js
@@ -39,6 +39,7 @@ cr.define('print_preview', function() {
     global['updatePrintPreview'] = this.onUpdatePrintPreview_.bind(this);
     global['printScalingDisabledForSourcePDF'] =
         this.onPrintScalingDisabledForSourcePDF_.bind(this);
+    global['onDidGetAccessToken'] = this.onDidGetAccessToken_.bind(this);
   };
 
   /**
@@ -47,6 +48,7 @@ cr.define('print_preview', function() {
    * @const
    */
   NativeLayer.EventType = {
+    ACCESS_TOKEN_READY: 'print_preview.NativeLayer.ACCESS_TOKEN_READY',
     CAPABILITIES_SET: 'print_preview.NativeLayer.CAPABILITIES_SET',
     CLOUD_PRINT_ENABLE: 'print_preview.NativeLayer.CLOUD_PRINT_ENABLE',
     DESTINATIONS_RELOAD: 'print_preview.NativeLayer.DESTINATIONS_RELOAD',
@@ -100,6 +102,14 @@ cr.define('print_preview', function() {
   NativeLayer.prototype = {
     __proto__: cr.EventTarget.prototype,
 
+    /**
+     * Requests access token for cloud print requests.
+     * @param {string} authType type of access token.
+     */
+    startGetAccessToken: function(authType) {
+      chrome.send('getAccessToken', [authType]);
+    },
+
     /** Gets the initial settings to initialize the print preview with. */
     startGetInitialSettings: function() {
       chrome.send('getInitialSettings');
@@ -520,6 +530,20 @@ cr.define('print_preview', function() {
     },
 
     /**
+     * Notification that access token is ready.
+     * @param {string} authType Type of access token.
+     * @param {string} accessToken Access token.
+     * @private
+     */
+    onDidGetAccessToken_: function(authType, accessToken) {
+      var getAccessTokenEvent = new cr.Event(
+          NativeLayer.EventType.ACCESS_TOKEN_READY);
+      getAccessTokenEvent.authType = authType;
+      getAccessTokenEvent.accessToken = accessToken;
+      this.dispatchEvent(getAccessTokenEvent);
+    },
+
+    /**
      * Update the print preview when new preview data is available.
      * Create the PDF plugin as needed.
      * Called from PrintPreviewUI::PreviewDataIsAvailable().