Make the scripting OOP PDF API easier to use (take 2)

chrome/browser/resources/pdf/pdf.js

 // Copyright 2013 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.
 
 'use strict';
 
 /**
  * @return {number} Width of a scrollbar in pixels
  */
 function getScrollbarWidth() {
@@ skipping 30 matching lines @@
  * document.
  * @constructor
  * @param {Object} streamDetails The stream object which points to the data
  *     contained in the PDF.
  */
 function PDFViewer(streamDetails) {
   this.streamDetails_ = streamDetails;
   this.loaded_ = false;
   this.parentWindow_ = null;
 
+  this.delayedScriptingMessages_ = [];
+
   this.isPrintPreview_ =
       this.streamDetails_.originalUrl.indexOf('chrome://print') == 0;
   this.isMaterial_ = location.pathname.substring(1) == 'index-material.html';
 
   // The sizer element is placed behind the plugin element to cause scrollbars
   // to be displayed in the window. It is sized according to the document size
   // of the pdf and zoom level.
   this.sizer_ = $('sizer');
   this.toolbar_ = $('toolbar');
   this.pageIndicator_ = $('page-indicator');
@@ skipping 272 matching lines @@
       if (this.passwordScreen_.active) {
         this.passwordScreen_.deny();
         this.passwordScreen_.active = false;
       }
     } else if (progress == 100) {
       // Document load complete.
       if (this.lastViewportPosition_)
         this.viewport_.position = this.lastViewportPosition_;
       this.handleURLParams_();
       this.loaded_ = true;
-      this.sendScriptingMessage_({
-        type: 'documentLoaded'
-      });
+      while (this.delayedScriptingMessages_.length > 0)
+        this.handleScriptingMessage(this.delayedScriptingMessages_.shift());
     }
   },
 
   /**
    * @private
    * An event handler for handling password-submitted events. These are fired
    * when an event is entered into the password screen.
    * @param {Object} event a password-submitted event.
    */
   onPasswordSubmitted_: function(event) {
@@ skipping 250 matching lines @@
       type: 'viewport',
       pageX: visiblePageDimensions.x,
       pageY: visiblePageDimensions.y,
       pageWidth: visiblePageDimensions.width,
       viewportWidth: size.width,
       viewportHeight: size.height
     });
   },
 
   /**
-   * @private
    * Handle a scripting message from outside the extension (typically sent by
    * PDFScriptingAPI in a page containing the extension) to interact with the
    * plugin.
    * @param {MessageObject} message the message to handle.
    */
   handleScriptingMessage: function(message) {
+    if (this.parentWindow_ != message.source)
+      this.parentWindow_ = message.source;
+
+    if (this.handlePrintPreviewScriptingMessage_(message))
+      return;
+
+    // Delay scripting messages from users of the scripting API until the
+    // document is loaded. This simplifies use of the APIs.
+    if (!this.loaded_) {
+      this.delayedScriptingMessages_.push(message);
+      return;
+    }
+
     switch (message.data.type.toString()) {
       case 'getAccessibilityJSON':
       case 'getSelectedText':
-      case 'loadPreviewPage':
       case 'print':
       case 'selectAll':
         this.plugin_.postMessage(message.data);
         break;
+      case 'isDocumentLoaded':
+        // Since this is only hit after the document has been loaded, we can
+        // send a reply immediately.
+        this.sendScriptingMessage_({
+          type: 'documentLoaded'
+        });
+        break;
+    }
+  },
+
+  /**
+   * @private
+   * Handle scripting messages specific to print preview.
+   * @param {MessageObject} message the message to handle.
+   * @return {boolean} true if the message was handled, false otherwise.
+   */
+  handlePrintPreviewScriptingMessage_: function(message) {
+    if (!this.isPrintPreview_)
+      return false;
+
+    switch (message.data.type.toString()) {
+      case 'loadPreviewPage':
+        this.plugin_.postMessage(message.data);
+        return true;
       case 'resetPrintPreviewMode':
-        if (!this.isPrintPreview_)
-          break;
-
         if (!this.inPrintPreviewMode_) {
           this.inPrintPreviewMode_ = true;
           this.viewport_.fitToPage();
         }
 
         // Stash the scroll location so that it can be restored when the new
         // document is loaded.
         this.lastViewportPosition_ = this.viewport_.position;
 
         // TODO(raymes): Disable these properly in the plugin.
         var printButton = $('print-button');
         if (printButton)
           printButton.parentNode.removeChild(printButton);
         var saveButton = $('save-button');
         if (saveButton)
           saveButton.parentNode.removeChild(saveButton);
 
         this.pageIndicator_.pageLabels = message.data.pageNumbers;
 
         this.plugin_.postMessage({
           type: 'resetPrintPreviewMode',
           url: message.data.url,
           grayscale: message.data.grayscale,
           // If the PDF isn't modifiable we send 0 as the page count so that no
           // blank placeholder pages get appended to the PDF.
           pageCount: (message.data.modifiable ?
                       message.data.pageNumbers.length : 0)
         });
-        break;
+        return true;
       case 'sendKeyEvent':
         var e = document.createEvent('Event');
         e.initEvent('scriptingKeypress');
         e.keyCode = message.data.keyCode;
         this.handleKeyEvent_(e);
-        break;
-      case 'setParentWindow':
-        if (this.parentWindow_ != message.source) {
-          this.parentWindow_ = message.source;
-          // If the document has already loaded, we always send a message that
-          // indicates that so that the embedder is aware.
-          if (this.loaded_) {
-            this.sendScriptingMessage_({
-              type: 'documentLoaded'
-            });
-          }
-        }
-        break;
+        return true;
     }
+
+    return false;
   },
 
   /**
    * @private
    * Send a scripting message outside the extension (typically to
    * PDFScriptingAPI in a page containing the extension).
    * @param {Object} message the message to send.
    */
   sendScriptingMessage_: function(message) {
     if (this.parentWindow_)
@@ skipping 11 matching lines @@
               this.streamDetails_.tabId != -1);
   },
 
   /**
    * @type {Viewport} the viewport of the PDF viewer.
    */
   get viewport() {
     return this.viewport_;
   }
 };