[Extensions] Don't show the pending URL for chrome.tabs API navigations

chrome/test/data/extensions/api_test/tabs/pdf_extension_test.html

Index: chrome/test/data/extensions/api_test/tabs/pdf_extension_test.html
diff --git a/chrome/test/data/extensions/api_test/tabs/pdf_extension_test.html b/chrome/test/data/extensions/api_test/tabs/pdf_extension_test.html
new file mode 100644
index 0000000000000000000000000000000000000000..bc235f8b90aadede8d554020bbdf7cb9c7ab9261
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/tabs/pdf_extension_test.html
@@ -0,0 +1,41 @@
+<script>
+onbeforeunload=function(){
+        document.write('<b>Welcome to {Some Website}</b>');
+        document.title='OtherWebsite.ltd';
+};
+</script>
+<embed type="application/pdf" src="data:application/pdf;base64,JVBERi0xLjcKIAp0cmFpbGVyCjw8Ci9Sb290IDEgMCBSCj4+CiAKMSAwIG9iago8PAovVHlwZSAvQ2F0YWxvZwovUGFnZXMgMiAwIFIKL09wZW5BY3Rpb24gMiAwIFIKPj4KZW5kb2JqCiAKMiAwIG9iago8PAovVHlwZSAvQWN0aW9uCi9TIC9VUkkKL1VSSSAoaHR0cDovL3d3dy5mYWNlYm9vay5jb206ODMpCj4+CmVuZG9iagogCiUlRU9G" width="640" height="480">
+
+
+<!--
+
+Source of the embeded PDF.
+
+-------------------------------------
+%PDF-1.7
+
+trailer
+<<
+/Root 1 0 R
+>>
+
+1 0 obj
+<<
+/Type /Catalog
+/Pages 2 0 R
+/OpenAction 2 0 R
+>>
+endobj
+
+2 0 obj
+<<
+/Type /Action
+/S /URI
+/URI (http://www.facebook.com:83)
+>>
+endobj
+
+%%EOF
+------------------------------------------
+
+-->