diff --git a/extensions/chrome/insertviewer.js b/extensions/chrome/insertviewer.js
index 6d39a1c31..82e106ead 100644
--- a/extensions/chrome/insertviewer.js
+++ b/extensions/chrome/insertviewer.js
@@ -27,6 +27,12 @@ function getViewerURL(pdf_url) {
 }
 
 function showViewer(url) {
+  if (document.documentElement === null) {
+    // If the root element hasn't been rendered yet, delay the next operation.
+    // Otherwise, document.readyState will get stuck in "interactive".
+    setTimeout(showViewer, 0, url);
+    return;
+  }
   // Cancel page load and empty document.
   window.stop();
   document.body.textContent = '';
diff --git a/extensions/chrome/manifest.json b/extensions/chrome/manifest.json
index 26dea5de1..e36274708 100644
--- a/extensions/chrome/manifest.json
+++ b/extensions/chrome/manifest.json
@@ -11,7 +11,8 @@
   "permissions": [
     "webRequest", "webRequestBlocking",
     "<all_urls>",
-    "tabs"
+    "tabs",
+    "webNavigation"
   ],
   "content_scripts": [{
       "matches": [
diff --git a/extensions/chrome/pdfHandler.js b/extensions/chrome/pdfHandler.js
index 28ba1a953..e4028f3dc 100644
--- a/extensions/chrome/pdfHandler.js
+++ b/extensions/chrome/pdfHandler.js
@@ -62,6 +62,28 @@ function insertPDFJSForTab(tabId, url) {
  * @param {string} url The URL of the pdf file.
  */
 function activatePDFJSForTab(tabId, url) {
+  if (!chrome.webNavigation) {
+    // Opera... does not support the webNavigation API.
+    activatePDFJSForTabFallbackForOpera(tabId, url);
+    return;
+  }
+  var listener = function webNavigationEventListener(details) {
+    if (details.tabId === tabId) {
+      insertPDFJSForTab(tabId, url);
+      chrome.webNavigation.onCommitted.removeListener(listener);
+    }
+  };
+  var urlFilter = {
+    url: [{ urlEquals: url }]
+  };
+  chrome.webNavigation.onCommitted.addListener(listener, urlFilter);
+}
+
+/**
+ * Fallback for Opera.
+ * @see activatePDFJSForTab
+ **/
+function activatePDFJSForTabFallbackForOpera(tabId, url) {
   chrome.tabs.onUpdated.addListener(function listener(_tabId) {
     if (tabId === _tabId) {
       insertPDFJSForTab(tabId, url);