PDFs viewed inside a <webview> should navigate the same as PDFs in tabs.

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 23 matching lines @@
     return decodeURIComponent(filename);
   } catch (e) {
     if (e instanceof URIError)
       return filename;
     throw e;
   }
 }
 
 /**
  * Called when navigation happens in the current tab.
+ * @param {int} tabId The id of the current tab; -1 if no current tab.

[Dan Beam, 2015/09/25 20:57:31]

there are no ints in javascript. this should be number

[wjmaclean, 2015/09/28 13:29:35]

Done.

  * @param {string} url The url to be opened in the current tab.
  */
-function onNavigateInCurrentTab(url) {
-  // Prefer the tabs API because it can navigate from one file:// URL to
-  // another.
-  if (chrome.tabs)
-    chrome.tabs.update({url: url});
+function onNavigateInCurrentTab(tabId, url) {
+  // When the PDFviewer is not inside a <webview>, prefer the tabs API because
+  // it can navigate from one file:// URL to another.
+  if (chrome.tabs && tabId != -1)
+    chrome.tabs.update(tabId, {url: url});
   else
     window.location.href = url;
 }
 
 /**
  * Called when navigation happens in the new tab.
  * @param {string} url The url to be opened in the new tab.
  */
 function onNavigateInNewTab(url) {
   // Prefer the tabs API because it guarantees we can just open a new tab.
@@ skipping 179 matching lines @@
   this.zoomManager_ = new ZoomManager(
       this.viewport_, this.browserApi_.setZoom.bind(this.browserApi_),
       this.browserApi_.getInitialZoom());
   this.browserApi_.addZoomEventListener(
       this.zoomManager_.onBrowserZoomChange.bind(this.zoomManager_));
 
   // Setup the keyboard event listener.
   document.addEventListener('keydown', this.handleKeyEvent_.bind(this));
   document.addEventListener('mousemove', this.handleMouseEvent_.bind(this));
 
+  var onNavigateBoundToCurrentTab = function(browserApi, url) {

[Dan Beam, 2015/09/25 20:57:31]

browserApi is already a local variable to this method, no need to bind it in
this method.  you can use browserApi from within the method without this param.

[wjmaclean, 2015/09/28 13:29:35]

Acknowledged.

+    var tabId = browserApi ? browserApi.getStreamInfo().tabId : -1;

[Dan Beam, 2015/09/25 20:57:31]

you're binding this.browserApi_ from outside, and it looks like that'll always
be truthy.  what is this ternary actually doing?

[wjmaclean, 2015/09/28 13:29:35]

Acknowledged.

+    onNavigateInCurrentTab(tabId, url);
+  }.bind(undefined, this.browserApi_);
+
   // Parse open pdf parameters.
   this.paramsParser_ =
       new OpenPDFParamsParser(this.getNamedDestination_.bind(this));
   this.navigator_ = new Navigator(this.browserApi_.getStreamInfo().originalUrl,
                                   this.viewport_, this.paramsParser_,
-                                  onNavigateInCurrentTab, onNavigateInNewTab);
+                                  onNavigateBoundToCurrentTab,

[raymes, 2015/09/27 23:02:02]

I think you should be able to delete onNavigateBoundToCurrentTab above and just
pass in:

onNavigateInCurrentTab.bind(undefined, browserApi.getStreamInfo().tabId)

[wjmaclean, 2015/09/28 13:29:35]

Ok.

I wasn't sure if it was safe to assume that the tabId value would never change,
hence why I originally wanted to check it each time the bound function was
called.

Done.

+                                  onNavigateInNewTab);
   this.viewportScroller_ =
       new ViewportScroller(this.viewport_, this.plugin_, window);
 }
 
 PDFViewer.prototype = {
   /**
    * @private
    * Handle key events. These may come from the user directly or via the
    * scripting API.
    * @param {KeyboardEvent} e the event to handle.
@@ skipping 606 matching lines @@
    * Each bookmark is an Object containing a:
    * - title
    * - page (optional)
    * - array of children (themselves bookmarks)
    * @type {Array} the top-level bookmarks of the PDF.
    */
   get bookmarks() {
     return this.bookmarks_;
   }
 };