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

chrome/browser/resources/pdf/pdf.js

Index: chrome/browser/resources/pdf/pdf.js
diff --git a/chrome/browser/resources/pdf/pdf.js b/chrome/browser/resources/pdf/pdf.js
index c8753e14a6207dca698cd16144c70cb57dba82f9..b22df900c03e5911bf06264b0dcf06e92acccff9 100644
--- a/chrome/browser/resources/pdf/pdf.js
+++ b/chrome/browser/resources/pdf/pdf.js
@@ -41,13 +41,14 @@ function getFilenameFromURL(url) {
 
 /**
  * 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;
 }
@@ -247,12 +248,18 @@ function PDFViewer(browserApi) {
   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);
 }