[CRX] Show nicely formatted URL in omnibox

Before commit:
chrome-extension://EXTENSIONID/content/web/viewer.html?file=http%3A%2F%2Fexample.com%2Ffile.pdf

After commit:
chrome-extension://EXTENSIONID/http://example/file.pdf

Technical details:
- The extension's background page uses the webRequest API to intercept
  requests for <extension host>/<real path to pdf>, and redirect it to
  the viewer's URL.
- viewer.js uses history.replaceState to rewrite the URL, so that it's
  easier for users to recognize and copy-paste URLs.
- The fake paths /http:, /https:, /file:, etc. have been added to the
  web_accessible_resources section of the manifest file, in order to
  avoid seeing chrome-extension://invalid/ instead of the actual URL
  when using history back/forward to navigate from/to the PDF viewer.
- Since the relative path resolving doesn't work because relative URLs
  are inaccurate, a <base> tag has been added. This method has already
  been proven to work in the Firefox add-on.

Notes:
- This commit has been cherry-picked from crx-using-streams-api.
- Need to merge https://github.com/mozilla/pdf.js/pull/3582 to deal with
  a bug in Chrome <=30
- In Chrome, getting the contents of a FTP file is not possible, so
  there's no support for FTP files, even though the extension router
  recognizes the ftp: scheme.

extensions/chromium/extension-router.js

@@ -0,0 +1,54 @@
+/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
+/*
+Copyright 2013 Mozilla Foundation
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+/* globals chrome */
+
+'use strict';
+(function ExtensionRouterClosure() {
+  var VIEWER_URL = chrome.extension.getURL('content/web/viewer.html');
+  var CRX_BASE_URL = chrome.extension.getURL('/');
+
+  // TODO(rob): Use declarativeWebRequest once declared URL-encoding is
+  //            supported, see http://crbug.com/273589
+  //            (or rewrite the query string parser in viewer.js to get it to
+  //             recognize the non-URL-encoded PDF URL.)
+  chrome.webRequest.onBeforeRequest.addListener(function(details) {
+    // This listener converts chrome-extension://.../http://...pdf to
+    // chrome-extension://.../content/web/viewer.html?file=http%3A%2F%2F...pdf
+    var url = details.url.substring(CRX_BASE_URL.length);
+    var matchingUrl = /^(?:https?|file|ftp|chrome-extension)(:|%3A)/.exec(url);
+    if (matchingUrl) {
+      // location.hash is restored when "#" is missing from URL.
+      url = url.split('#')[0];
+      if (matchingUrl[1] === ':') {
+        url = encodeURIComponent(url);
+      }
+      url = VIEWER_URL + '?file=' + url;
+      console.log('Redirecting ' + details.url + ' to ' + url);
+      return { redirectUrl: url };
+    }
+  }, {
+      types: ['main_frame', 'sub_frame'],
+      urls: [
+        CRX_BASE_URL + 'http*', // and https
+        CRX_BASE_URL + 'file*',
+        CRX_BASE_URL + 'ftp*',
+        CRX_BASE_URL + 'chrome-extension*'
+      ]
+  }, ['blocking']);
+  console.log('Set up extension URL router.');
+})();

extensions/chromium/manifest.json

@@ -24,6 +24,11 @@
   "incognito": "split",
   "web_accessible_resources": [
     "getFrameId",
-    "content/web/viewer.html"
+    "content/web/viewer.html",
+    "http:/*",
+    "https:/*",
+    "ftp:/*",
+    "file:/*",
+    "chrome-extension:/*"
   ]
 }

extensions/chromium/pdfHandler.html

@@ -16,3 +16,4 @@ limitations under the License.
 -->
 <script src="chrome.tabs.executeScriptInFrame.js"></script>
 <script src="pdfHandler.js"></script>
+<script src="extension-router.js"></script>

web/viewer-snippet-chrome-extension.html

@@ -0,0 +1,5 @@
+<!-- This snippet is used in the Chrome extension, see Makefile -->
+<base href="/content/web/">
+<link rel="resource" type="application/l10n" href="locale/locale.properties">
+<script type="text/javascript" src="l10n.js"></script>
+<script type="text/javascript" src="../build/pdf.js"></script>

web/viewer.html

@@ -25,6 +25,9 @@ limitations under the License.
 
 <!--#if FIREFOX || MOZCENTRAL-->
 <!--#include viewer-snippet-firefox-extension.html-->
+<!--#endif-->
+<!--#if CHROME-->
+<!--#include viewer-snippet-chrome-extension.html-->
 <!--#endif-->
 
     <link rel="stylesheet" href="viewer.css"/>
@@ -53,7 +56,7 @@ limitations under the License.
     <script type="text/javascript">PDFJS.workerSrc = '../src/worker_loader.js';</script>
 <!--#endif-->
 
-<!--#if GENERIC || CHROME-->
+<!--#if GENERIC -->
 <!--#include viewer-snippet.html-->
 <!--#endif-->
 

web/viewer.js

@@ -670,15 +670,19 @@ var PDFView = {
   },
 
   /**
-   * For the firefox extension we prefix the full url on anchor links so they
-   * don't come up as resource:// urls and so open in new tab/window works.
-   * @param {String} anchor The anchor hash include the #.
+   * Prefix the full url on anchor links to make sure that links are resolved
+   * relative to the current URL instead of the one defined in <base href>.
+   * @param {String} anchor The anchor hash, including the #.
    */
   getAnchorUrl: function getAnchorUrl(anchor) {
-//#if !(FIREFOX || MOZCENTRAL)
+//#if !(FIREFOX || MOZCENTRAL || CHROME)
     return anchor;
 //#else
+//#if CHROME
+//  return location.href.split('#')[0] + anchor;
+//#else
 //  return this.url.split('#')[0] + anchor;
+//#endif
 //#endif
   },
 
@@ -1459,15 +1463,36 @@ var DocumentOutlineView = function documentOutlineView(outline) {
   }
 };
 
+//#if CHROME
+//(function rewriteUrlClosure() {
+//  // Run this code outside DOMContentLoaded to make sure that the URL
+//  // is rewritten as soon as possible.
+//  if (location.origin + '/' !== chrome.extension.getURL('/')) {
+//    DEFAULT_URL = window.location.href.split('#')[0];
+//  } else {
+//    var params = PDFView.parseQueryString(document.location.search.slice(1));
+//    DEFAULT_URL = params.file || DEFAULT_URL;
+//
+//    // Example: chrome-extension://.../http://example.com/file.pdf
+//    var humanReadableUrl = '/' + DEFAULT_URL + location.hash;
+//    history.replaceState(history.state, '', humanReadableUrl);
+//  }
+//})();
+//#endif
+
 document.addEventListener('DOMContentLoaded', function webViewerLoad(evt) {
   PDFView.initialize();
 
-//#if !(FIREFOX || MOZCENTRAL)
+//#if !(FIREFOX || MOZCENTRAL || CHROME)
   var params = PDFView.parseQueryString(document.location.search.substring(1));
   var file = params.file || DEFAULT_URL;
 //#else
+//#if CHROME
+//var file = DEFAULT_URL;
+//#else
 //var file = window.location.href.split('#')[0];
 //#endif
+//#endif
 
 //#if CHROME
 //if (location.protocol !== 'chrome-extension:') {